diff --git a/common/sab.js b/common/sab.js
index a3ea610e165d0d..565d81eb566258 100644
--- a/common/sab.js
+++ b/common/sab.js
@@ -1,4 +1,4 @@
-const createBuffer = (() => {
+globalThis.createBuffer = (() => {
   // See https://github.com/whatwg/html/issues/5380 for why not `new SharedArrayBuffer()`
   let sabConstructor;
   try {
diff --git a/html/webappapis/structured-clone/structured-clone-battery-of-tests-harness.js b/html/webappapis/structured-clone/structured-clone-battery-of-tests-harness.js
index 00a86fa74b9a96..5e420ca212a068 100644
--- a/html/webappapis/structured-clone/structured-clone-battery-of-tests-harness.js
+++ b/html/webappapis/structured-clone/structured-clone-battery-of-tests-harness.js
@@ -19,14 +19,16 @@ function runStructuredCloneBatteryOfTests(runner) {
     preTest() {},
     postTest() {},
     teardown() {},
-    hasDocument: true
+    hasDocument: true,
+    hasBlob: true,
   };
   runner = Object.assign({}, defaultRunner, runner);
 
   let setupPromise = runner.setup();
   const allTests = structuredCloneBatteryOfTests.map(test => {
 
-    if (!runner.hasDocument && test.requiresDocument) {
+    if ((!runner.hasDocument && test.requiresDocument) ||
+        (!runner.hasBlob && test.requiresBlob)) {
       return;
     }
 
@@ -43,3 +45,4 @@ function runStructuredCloneBatteryOfTests(runner) {
   });
   Promise.all(allTests).then(_ => runner.teardown());
 }
+globalThis.runStructuredCloneBatteryOfTests = runStructuredCloneBatteryOfTests;
diff --git a/html/webappapis/structured-clone/structured-clone-battery-of-tests-with-transferables.js b/html/webappapis/structured-clone/structured-clone-battery-of-tests-with-transferables.js
index 23cf4f651ac70a..310a0878d51b5b 100644
--- a/html/webappapis/structured-clone/structured-clone-battery-of-tests-with-transferables.js
+++ b/html/webappapis/structured-clone/structured-clone-battery-of-tests-with-transferables.js
@@ -1,3 +1,30 @@
+// Feature detection.
+// MessagePort is not Exposed=*, so skip MessagePort-specific tests if it is not
+// present.
+// Streams, e.g. ReadableStream, are both Exposed=* and Transferable, but the
+// transferability is not widely implemented.
+// For tests that need _any_ transferable object, use one or the other in order
+// to make the test as useful as possible. If neither is available, skip the
+// test since transferability of streams is not specifically being tested here.
+// There are tests specifically for the transferability of streams in
+// streams/transferable/.
+
+const environmentHasMessagePort = typeof globalThis.MessagePort !== 'undefined' &&
+  typeof globalThis.MessageChannel !== 'undefined';
+
+function readableStreamIsTransferable() {
+  try {
+    const stream = new ReadableStream();
+    structuredClone(stream, [stream]);
+    return true;
+  } catch(err) {
+    if (err instanceof DOMException && err.code === DOMException.DATA_CLONE_ERR) {
+      return false;
+    }
+    throw err;
+  }
+}
+
 structuredCloneBatteryOfTests.push({
   description: 'ArrayBuffer',
   async f(runner) {
@@ -8,16 +35,18 @@ structuredCloneBatteryOfTests.push({
   }
 });
 
-structuredCloneBatteryOfTests.push({
-  description: 'MessagePort',
-  async f(runner) {
-    const {port1, port2} = new MessageChannel();
-    const copy = await runner.structuredClone(port2, [port2]);
-    const msg = new Promise(resolve => port1.onmessage = resolve);
-    copy.postMessage('ohai');
-    assert_equals((await msg).data, 'ohai');
-  }
-});
+if (environmentHasMessagePort) {
+  structuredCloneBatteryOfTests.push({
+    description: 'MessagePort',
+    async f(runner) {
+      const {port1, port2} = new MessageChannel();
+      const copy = await runner.structuredClone(port2, [port2]);
+      const msg = new Promise(resolve => port1.onmessage = resolve);
+      copy.postMessage('ohai');
+      assert_equals((await msg).data, 'ohai');
+    }
+  });
+}
 
 // TODO: ImageBitmap
 
@@ -37,12 +66,19 @@ structuredCloneBatteryOfTests.push({
 structuredCloneBatteryOfTests.push({
   description: 'A detached platform object cannot be transferred',
   async f(runner, t) {
-    const {port1} = new MessageChannel();
-    await runner.structuredClone(port1, [port1]);
+    let xferable;
+    if (environmentHasMessagePort) {
+      xferable = new MessageChannel().port1;
+    } else if (readableStreamIsTransferable()) {
+      xferable = new ReadableStream();
+    } else {
+      throw new OptionalFeatureUnsupportedError('No suitable exposed and transferable platform object to test');
+    }
+    await runner.structuredClone(xferable, [xferable]);
     await promise_rejects_dom(
       t,
       "DataCloneError",
-      runner.structuredClone(port1, [port1])
+      runner.structuredClone(xferable, [xferable])
     );
   }
 });
@@ -50,26 +86,36 @@ structuredCloneBatteryOfTests.push({
 structuredCloneBatteryOfTests.push({
   description: 'Transferring a non-transferable platform object fails',
   async f(runner, t) {
-    const blob = new Blob();
+    const exc = new DOMException();
     await promise_rejects_dom(
       t,
       "DataCloneError",
-      runner.structuredClone(blob, [blob])
+      runner.structuredClone(exc, [exc])
     );
-  }
+  },
 });
 
 structuredCloneBatteryOfTests.push({
   description: 'An object whose interface is deleted from the global object must still be received',
   async f(runner) {
-    const {port1} = new MessageChannel();
-    const messagePortInterface = globalThis.MessagePort;
-    delete globalThis.MessagePort;
+    let xferable, iface, globalPropName;
+    if (environmentHasMessagePort) {
+      xferable = new MessageChannel().port1;
+      iface = globalThis.MessagePort;
+      globalPropName = 'MessagePort';
+    } else if (readableStreamIsTransferable()) {
+      xferable = new ReadableStream();
+      iface = globalThis.ReadableStream;
+      globalPropName = 'ReadableStream';
+    } else {
+      throw new OptionalFeatureUnsupportedError('No suitable exposed and transferable platform object to test');
+    }
+    delete globalThis[globalPropName];
     try {
-      const transfer = await runner.structuredClone(port1, [port1]);
-      assert_true(transfer instanceof messagePortInterface);
+      const transfer = await runner.structuredClone(xferable, [xferable]);
+      assert_true(transfer instanceof iface);
     } finally {
-      globalThis.MessagePort = messagePortInterface;
+      globalThis[globalPropName] = iface;
     }
   }
 });
@@ -79,16 +125,8 @@ structuredCloneBatteryOfTests.push({
   async f(runner) {
     // MessagePort doesn't have a constructor, so we must use something else.
 
-    // Make sure that ReadableStream is transferable before we test its subclasses.
-    try {
-      const stream = new ReadableStream();
-      await runner.structuredClone(stream, [stream]);
-    } catch(err) {
-      if (err instanceof DOMException && err.code === DOMException.DATA_CLONE_ERR) {
-        throw new OptionalFeatureUnsupportedError("ReadableStream isn't transferable");
-      } else {
-        throw err;
-      }
+    if (!readableStreamIsTransferable()) {
+      throw new OptionalFeatureUnsupportedError('No suitable subclassable, exposed, and transferable platform object to test');
     }
 
     class ReadableStreamSubclass extends ReadableStream {}
diff --git a/html/webappapis/structured-clone/structured-clone-battery-of-tests.js b/html/webappapis/structured-clone/structured-clone-battery-of-tests.js
index 923ac9dc164918..a59fc6063a4ce9 100644
--- a/html/webappapis/structured-clone/structured-clone-battery-of-tests.js
+++ b/html/webappapis/structured-clone/structured-clone-battery-of-tests.js
@@ -1,8 +1,8 @@
 /* This file is mostly a remix of @zcorpan’s web worker test suite */
 
-structuredCloneBatteryOfTests = [];
+globalThis.structuredCloneBatteryOfTests = [];
 
-function check(description, input, callback, requiresDocument = false) {
+function check(description, input, callback, requiresDocument = false, requiresBlob = false) {
   structuredCloneBatteryOfTests.push({
     description,
     async f(runner) {
@@ -13,7 +13,8 @@ function check(description, input, callback, requiresDocument = false) {
       const copy = await runner.structuredClone(newInput);
       await callback(copy, newInput);
     },
-    requiresDocument
+    requiresDocument,
+    requiresBlob,
   });
 }
 
@@ -296,7 +297,7 @@ async function compare_Blob(actual, input, expect_File) {
 function func_Blob_basic() {
   return new Blob(['foo'], {type:'text/x-bar'});
 }
-check('Blob basic', func_Blob_basic, compare_Blob);
+check('Blob basic', func_Blob_basic, compare_Blob, false, true);
 
 function b(str) {
   return parseInt(str, 2);
@@ -322,33 +323,33 @@ function func_Blob_bytes(arr) {
     return new Blob([view]);
   };
 }
-check('Blob unpaired high surrogate (invalid utf-8)', func_Blob_bytes(encode_cesu8([0xD800])), compare_Blob);
-check('Blob unpaired low surrogate (invalid utf-8)', func_Blob_bytes(encode_cesu8([0xDC00])), compare_Blob);
-check('Blob paired surrogates (invalid utf-8)', func_Blob_bytes(encode_cesu8([0xD800, 0xDC00])), compare_Blob);
+check('Blob unpaired high surrogate (invalid utf-8)', func_Blob_bytes(encode_cesu8([0xD800])), compare_Blob, false, true);
+check('Blob unpaired low surrogate (invalid utf-8)', func_Blob_bytes(encode_cesu8([0xDC00])), compare_Blob, false, true);
+check('Blob paired surrogates (invalid utf-8)', func_Blob_bytes(encode_cesu8([0xD800, 0xDC00])), compare_Blob, false, true);
 
 function func_Blob_empty() {
   return new Blob(['']);
 }
-check('Blob empty', func_Blob_empty , compare_Blob);
+check('Blob empty', func_Blob_empty , compare_Blob, false, true);
 function func_Blob_NUL() {
   return new Blob(['\u0000']);
 }
-check('Blob NUL', func_Blob_NUL, compare_Blob);
+check('Blob NUL', func_Blob_NUL, compare_Blob, false, true);
 
-check('Array Blob object, Blob basic', [func_Blob_basic()], compare_Array(enumerate_props(compare_Blob)));
-check('Array Blob object, Blob unpaired high surrogate (invalid utf-8)', [func_Blob_bytes([0xD800])()], compare_Array(enumerate_props(compare_Blob)));
-check('Array Blob object, Blob unpaired low surrogate (invalid utf-8)', [func_Blob_bytes([0xDC00])()], compare_Array(enumerate_props(compare_Blob)));
-check('Array Blob object, Blob paired surrogates (invalid utf-8)', [func_Blob_bytes([0xD800, 0xDC00])()], compare_Array(enumerate_props(compare_Blob)));
-check('Array Blob object, Blob empty', [func_Blob_empty()], compare_Array(enumerate_props(compare_Blob)));
-check('Array Blob object, Blob NUL', [func_Blob_NUL()], compare_Array(enumerate_props(compare_Blob)));
-check('Array Blob object, two Blobs', [func_Blob_basic(), func_Blob_empty()], compare_Array(enumerate_props(compare_Blob)));
+check('Array Blob object, Blob basic', () => [func_Blob_basic()], compare_Array(enumerate_props(compare_Blob)), false, true);
+check('Array Blob object, Blob unpaired high surrogate (invalid utf-8)', () => [func_Blob_bytes([0xD800])()], compare_Array(enumerate_props(compare_Blob)), false, true);
+check('Array Blob object, Blob unpaired low surrogate (invalid utf-8)', () => [func_Blob_bytes([0xDC00])()], compare_Array(enumerate_props(compare_Blob)), false, true);
+check('Array Blob object, Blob paired surrogates (invalid utf-8)', () => [func_Blob_bytes([0xD800, 0xDC00])()], compare_Array(enumerate_props(compare_Blob)), false, true);
+check('Array Blob object, Blob empty', () => [func_Blob_empty()], compare_Array(enumerate_props(compare_Blob)), false, true);
+check('Array Blob object, Blob NUL', () => [func_Blob_NUL()], compare_Array(enumerate_props(compare_Blob)), false, true);
+check('Array Blob object, two Blobs', () => [func_Blob_basic(), func_Blob_empty()], compare_Array(enumerate_props(compare_Blob)), false, true);
 
-check('Object Blob object, Blob basic', {'x':func_Blob_basic()}, compare_Object(enumerate_props(compare_Blob)));
-check('Object Blob object, Blob unpaired high surrogate (invalid utf-8)', {'x':func_Blob_bytes([0xD800])()}, compare_Object(enumerate_props(compare_Blob)));
-check('Object Blob object, Blob unpaired low surrogate (invalid utf-8)', {'x':func_Blob_bytes([0xDC00])()}, compare_Object(enumerate_props(compare_Blob)));
-check('Object Blob object, Blob paired surrogates (invalid utf-8)', {'x':func_Blob_bytes([0xD800, 0xDC00])()  }, compare_Object(enumerate_props(compare_Blob)));
-check('Object Blob object, Blob empty', {'x':func_Blob_empty()}, compare_Object(enumerate_props(compare_Blob)));
-check('Object Blob object, Blob NUL', {'x':func_Blob_NUL()}, compare_Object(enumerate_props(compare_Blob)));
+check('Object Blob object, Blob basic', () => ({'x':func_Blob_basic()}), compare_Object(enumerate_props(compare_Blob)), false, true);
+check('Object Blob object, Blob unpaired high surrogate (invalid utf-8)', () => ({'x':func_Blob_bytes([0xD800])()}), compare_Object(enumerate_props(compare_Blob)), false, true);
+check('Object Blob object, Blob unpaired low surrogate (invalid utf-8)', () => ({'x':func_Blob_bytes([0xDC00])()}), compare_Object(enumerate_props(compare_Blob)), false, true);
+check('Object Blob object, Blob paired surrogates (invalid utf-8)', () => ({'x':func_Blob_bytes([0xD800, 0xDC00])()}), compare_Object(enumerate_props(compare_Blob)), false, true);
+check('Object Blob object, Blob empty', () => ({'x':func_Blob_empty()}), compare_Object(enumerate_props(compare_Blob)), false, true);
+check('Object Blob object, Blob NUL', () => ({'x':func_Blob_NUL()}), compare_Object(enumerate_props(compare_Blob)), false, true);
 
 async function compare_File(actual, input) {
   assert_true(actual instanceof File, 'instanceof File');
@@ -359,7 +360,7 @@ async function compare_File(actual, input) {
 function func_File_basic() {
   return new File(['foo'], 'bar', {type:'text/x-bar', lastModified:42});
 }
-check('File basic', func_File_basic, compare_File);
+check('File basic', func_File_basic, compare_File, false, true);
 
 function compare_FileList(actual, input) {
   if (typeof actual === 'string')
@@ -643,11 +644,11 @@ check('ObjectPrototype must lose its exotic-ness when cloned',
 structuredCloneBatteryOfTests.push({
   description: 'Serializing a non-serializable platform object fails',
   async f(runner, t) {
-    const request = new Response();
+    const ac = new AbortController();
     await promise_rejects_dom(
       t,
       "DataCloneError",
-      runner.structuredClone(request)
+      runner.structuredClone(ac)
     );
   }
 });
@@ -655,27 +656,40 @@ structuredCloneBatteryOfTests.push({
 structuredCloneBatteryOfTests.push({
   description: 'An object whose interface is deleted from the global must still deserialize',
   async f(runner) {
-    const blob = new Blob();
-    const blobInterface = globalThis.Blob;
-    delete globalThis.Blob;
+    const domException = new DOMException();
+    const domExceptionInterface = globalThis.DOMException;
+    delete globalThis.DOMException;
     try {
-      const copy = await runner.structuredClone(blob);
-      assert_true(copy instanceof blobInterface);
+      const copy = await runner.structuredClone(domException);
+      assert_true(copy instanceof domExceptionInterface);
     } finally {
-      globalThis.Blob = blobInterface;
+      globalThis.DOMException = domExceptionInterface;
     }
-  }
+  },
 });
 
 check(
   'A subclass instance will deserialize as its closest serializable superclass',
+  () => {
+    class DOMExceptionSubclass extends DOMException {}
+    return new DOMExceptionSubclass([], "");
+  },
+  (copy) => {
+    assert_equals(Object.getPrototypeOf(copy), DOMException.prototype);
+  }
+);
+
+check(
+  'A subclass instance will deserialize as its closest serializable superclass when there are multiple serializable superclasses',
   () => {
     class FileSubclass extends File {}
     return new FileSubclass([], "");
   },
   (copy) => {
-    assert_equals(Object.getPrototypeOf(copy), File.prototype);
-  }
+    assert_equals(Object.getPrototypeOf(copy), File.prototype, "Prototype is File, not Blob");
+  },
+  false,
+  true
 );
 
 check(
diff --git a/html/webappapis/structured-clone/structured-clone.any.js b/html/webappapis/structured-clone/structured-clone.any.js
index 1358a71fc03d4e..781f7c32332557 100644
--- a/html/webappapis/structured-clone/structured-clone.any.js
+++ b/html/webappapis/structured-clone/structured-clone.any.js
@@ -1,4 +1,5 @@
 // META: title=structuredClone() tests
+// META: global=window,dedicatedworker,shadowrealm
 // META: script=/common/sab.js
 // META: script=/html/webappapis/structured-clone/structured-clone-battery-of-tests.js
 // META: script=/html/webappapis/structured-clone/structured-clone-battery-of-tests-with-transferables.js
@@ -11,4 +12,5 @@ runStructuredCloneBatteryOfTests({
     });
   },
   hasDocument: typeof document !== "undefined",
+  hasBlob: typeof Blob !== "undefined",
 });