Experiment with blocking script inside fragment-parser-inserted `<iframe srcdoc>`.

third_party/WebKit/Source/core/loader/FrameFetchContextTest.cpp

 /*
  * Copyright (c) 2015, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 362 matching lines @@
 TEST_F(FrameFetchContextModifyRequestTest, SendEmbeddingCSPHeader) {
   struct TestCase {
     const char* toRequest;
     WebURLRequest::FrameType frameType;
   } tests[] = {
       {"https://example.test/page.html", WebURLRequest::FrameTypeAuxiliary},
       {"https://example.test/page.html", WebURLRequest::FrameTypeNested},
       {"https://example.test/page.html", WebURLRequest::FrameTypeNone},
       {"https://example.test/page.html", WebURLRequest::FrameTypeTopLevel}};
 
-  HTMLIFrameElement* iframe = HTMLIFrameElement::create(*document);
+  HTMLIFrameElement* iframe = HTMLIFrameElement::create(*document, false);
   const AtomicString& requiredCSP = AtomicString("default-src 'none'");
   const AtomicString& anotherRequiredCSP = AtomicString("default-src 'self'");
 
   for (const auto& test : tests) {
     setFrameOwnerBasedOnFrameType(test.frameType, iframe, requiredCSP);
     expectSetEmbeddingCSPRequestHeader(
         test.toRequest, test.frameType,
         test.frameType == WebURLRequest::FrameTypeNested ? requiredCSP
                                                          : nullAtom);
 
@@ skipping 409 matching lines @@
     fetchContext->addAdditionalRequestHeaders(mainRequest, FetchMainResource);
     EXPECT_EQ(test.isExternalExpectation, mainRequest.isExternalRequest());
 
     ResourceRequest subRequest(test.url);
     fetchContext->addAdditionalRequestHeaders(subRequest, FetchSubresource);
     EXPECT_EQ(test.isExternalExpectation, subRequest.isExternalRequest());
   }
 }
 
 }  // namespace blink