Dyno: add test for issue #11225 (#26464)

In production, the issue (presumably) persists. However, in Dyno
everything looks like it works as we'd expect. So, locking down the test
case to ensure subsequent changes to Dyno don't break it.

Trivial, will not be reviewed.

## Testing
- [x] dyno tests

frontend/test/resolution/testPromotion.cpp

@@ -388,6 +388,39 @@ static void test18() {
 
 }
 
+static void test19() {
+  // promotion on multiple arguments with default arguments
+  runProgram(
+      { "proc foo(x: int = 1, y: int = 2) do return true;",
+        "for i in foo(1, new R()) {}" },
+      [](ErrorGuard& guard, const QualifiedType& t) {
+        assert(!t.isUnknownOrErroneous());
+        assert(t.type()->isBoolType());
+      },
+      IterableType("R").definePromotionType("int")
+        .defineSerialIterator("1"));
+
+  runProgram(
+      { "proc foo(x: int = 1, y: int = 2) do return true;",
+        "for i in foo(x=new R()) {}" },
+      [](ErrorGuard& guard, const QualifiedType& t) {
+        assert(!t.isUnknownOrErroneous());
+        assert(t.type()->isBoolType());
+      },
+      IterableType("R").definePromotionType("int")
+        .defineSerialIterator("1"));
+
+  runProgram(
+      { "proc foo(x: int = 1, y: int = 2) do return true;",
+        "for i in foo(y=new R()) {}" },
+      [](ErrorGuard& guard, const QualifiedType& t) {
+        assert(!t.isUnknownOrErroneous());
+        assert(t.type()->isBoolType());
+      },
+      IterableType("R").definePromotionType("int")
+        .defineSerialIterator("1"));
+}
+
 static void testTertiaryMethod() {
   // tertiary method definitions of chpl__promotionType
   // (defined in the scope of iteration) are not allowed.
@@ -449,6 +482,7 @@ int main() {
     test16();
     test17();
     test18();
+    test19();
   }
 
   testTertiaryMethod();