Use Shadow DOM to display fallback content for images

Source/web/tests/ActivityLoggerTest.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 
 #include "FrameTestHelpers.h"
 #include "bindings/core/v8/ScriptController.h"
 #include "bindings/core/v8/V8Binding.h"
 #include "bindings/core/v8/V8DOMActivityLogger.h"
@@ skipping 498 matching lines @@
         "document.close();"
         "var xhr = new XMLHttpRequest(); xhr.open('GET', 'data:text/html;charset=utf-8,E'); xhr.send();";
     const char* expectedActivities =
         "blinkAddElement | iframe | data:text/html;charset=utf-8,A\n"
         "blinkRequestResource | Main resource | data:text/html;charset=utf-8,A\n"
         "blinkRequestResource | Image | data:text/html;charset=utf-8,B\n"
         "blinkAddElement | link | stylesheet | data:text/html;charset=utf-8,C\n"
         "blinkRequestResource | CSS stylesheet | data:text/html;charset=utf-8,C\n"
         "blinkAddElement | script | data:text/html;charset=utf-8,D\n"
         "blinkRequestResource | Script | data:text/html;charset=utf-8,D\n"
-        "blinkRequestResource | XMLHttpRequest | data:text/html;charset=utf-8,E";
+        "blinkRequestResource | XMLHttpRequest | data:text/html;charset=utf-8,E\n"
+        "blinkRequestResource | Image | data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAIAAACQkWg2AAABO0lEQVR4XpWRTytEYRTG3/tHLGQrNfEBpKQkmc8gG0ulxpRsfQ0TTXbI3kZ2ys4tsyBZjN1N8idlYUYaxJzzOKf7ztG1MfN0ens69/x6n/eeYPuo7npS9bCOriXDMQOCTVbO3X+6Wp9mICZWAHqquE1qAA8EQRiFcmYMsQKsAHM2DeKV4qj48ZHB++bHwcXTQ+Mz6u/rABwSIQO0wKW5wuLU8E5yWzlJS7OFvaUJMGelAFkkYici1NIXB4DQbH1JY2ggVoD4N1Kb2AAA149vUmLLxbHaTaNynIJggAz7G7jTyjB5wOv79/LupT47Cu0rcT6S/ai755YUiMM4cgw4/I3ERAaI3y/PiFnYPHOBtfORLKX38AaBERaJbHFeAOY3Eu8ZOYByi7Pl+hzWN+nwWjVB15LhYHXr1PWiH0AYTw4BBjO9AAAAAElFTkSuQmCC";
     executeScriptInMainWorld(code);
     ASSERT_TRUE(verifyActivities(""));
     executeScriptInIsolatedWorld(code);
     ASSERT_TRUE(verifyActivities(expectedActivities));
 }
 
 } // namespace