Cherry pick the FakeXMLHttpRequest fix from #761 (#763)

Cherry pick the `FakeXMLHttpRequest` fix from #761 onto the `b3.10` branch.

This ugly PR patches `FakeXMLHttpRequest` based on the discoveries from @VictorSoroka1 in 

pretenderjs/FakeXMLHttpRequest#54

which were introduced by:

https://github.com/pretenderjs/FakeXMLHttpRequest/pull/53/files

The changes introduced here together with the PR from @VictorSoroka1  in:

folio-org/stripes-smart-components#677

should hopefully resolve the test issues. 

This is a temporary fix until we can get the Mirage dependency updated.

test/bigtest/network/patch-fake-xml-http-request.js

@@ -0,0 +1,123 @@
+/* eslint-disable */
+import FakeXMLHttpRequest from 'fake-xml-http-request';
+
+/**
+ * Monkey patch FakeXMLHttpRequest and remove `response` based on the work in:
+ * https://github.com/pretenderjs/FakeXMLHttpRequest/pull/53/files
+ *
+ * which caused the issue described under:
+ *
+ * https://github.com/pretenderjs/FakeXMLHttpRequest/issues/54
+ *
+ */
+
+FakeXMLHttpRequest.prototype.open = function(method, url, async, username, password) {
+  this.method = method;
+  this.url = url;
+  this.async = typeof async == "boolean" ? async : true;
+  this.username = username;
+  this.password = password;
+  this.responseText = null;
+  this.responseXML = null;
+  this.responseURL = url;
+  this.requestHeaders = {};
+  this.sendFlag = false;
+  delete this.response;
+  this._readyStateChange(FakeXMLHttpRequest.OPENED);
+}
+
+FakeXMLHttpRequest.prototype.abort = function() {
+  this.aborted = true;
+  this.responseText = null;
+  delete this.response;
+  this.errorFlag = true;
+  this.requestHeaders = {};
+
+  this.dispatchEvent(new _Event("abort", false, false, this));
+
+  if (this.readyState > FakeXMLHttpRequest.UNSENT && this.sendFlag) {
+    this._readyStateChange(FakeXMLHttpRequest.UNSENT);
+    this.sendFlag = false;
+  }
+
+  if (typeof this.onerror === "function") {
+    this.onerror();
+  }
+}
+
+FakeXMLHttpRequest.prototype._setResponseBody = function (body) {
+  verifyRequestSent(this);
+  verifyHeadersReceived(this);
+  verifyResponseBodyType(body);
+
+  var chunkSize = this.chunkSize || 10;
+  var index = 0;
+  this.responseText = "";
+  delete this.response;
+
+  do {
+    if (this.async) {
+      this._readyStateChange(FakeXMLHttpRequest.LOADING);
+    }
+
+    this.responseText += body.substring(index, index + chunkSize);
+    index += chunkSize;
+  } while (index < body.length);
+
+  var type = this.getResponseHeader("Content-Type");
+
+  if (this.responseText && (!type || /(text\/xml)|(application\/xml)|(\+xml)/.test(type))) {
+    try {
+      this.responseXML = parseXML(this.responseText);
+    } catch (e) {
+      // Unable to parse XML - no biggie
+    }
+  }
+
+  if (this.async) {
+    this._readyStateChange(FakeXMLHttpRequest.DONE);
+  } else {
+    this.readyState = FakeXMLHttpRequest.DONE;
+  }
+};
+
+function verifyRequestSent(xhr) {
+  if (xhr.readyState == FakeXMLHttpRequest.DONE) {
+      throw new Error("Request done");
+  }
+}
+
+function verifyHeadersReceived(xhr) {
+  if (xhr.async && xhr.readyState != FakeXMLHttpRequest.HEADERS_RECEIVED) {
+      throw new Error("No headers received");
+  }
+}
+
+function verifyResponseBodyType(body) {
+  if (typeof body != "string") {
+      var error = new Error("Attempted to respond to fake XMLHttpRequest with " +
+                           body + ", which is not a string.");
+      error.name = "InvalidBodyException";
+      throw error;
+  }
+}
+
+/*
+  Cross-browser XML parsing. Used to turn
+  XML responses into Document objects
+  Borrowed from JSpec
+*/
+function parseXML(text) {
+  var xmlDoc;
+
+  if (typeof DOMParser != "undefined") {
+    var parser = new DOMParser();
+    xmlDoc = parser.parseFromString(text, "text/xml");
+  } else {
+    xmlDoc = new ActiveXObject("Microsoft.XMLDOM");
+    xmlDoc.async = "false";
+    xmlDoc.loadXML(text);
+  }
+
+  return xmlDoc;
+}

test/bigtest/network/start.js

@@ -10,7 +10,7 @@ if (environment !== 'production') {
   const { default: Mirage, camelize } = require('@bigtest/mirage');
   const { default: coreModules } = require('./index');
   require('./force-fetch-polyfill');
-  require('./patch-response-url');
+  require('./patch-fake-xml-http-request');
 
   start = (scenarioNames, options = {}) => {
     const {