Change snasphotting API to take in a bounds Rect

chrome/test/data/gpu/webgl_teapot/teapot_files/demo.js

 /*
  * Copyright (c) 2009 The Chromium Authors. 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 368 matching lines @@
                 waitForFinish();
             }
         }(texture, face, image, url);
         image.src = url;
     }
     return texture;
 }
 
 function waitForFinish() {
   if (g_pendingTextureLoads == 0) {
-    domAutomationController.setAutomationId(1);
-    domAutomationController.send("ok");
+    var epilogue = document.createElement("script");
+    epilogue.onload = function() {
+      domAutomationController.setAutomationId(1);
+      domAutomationController.send("ok");
+    }
+    epilogue.src = "./teapot_files/epilogue.js";
+    document.body.appendChild(epilogue);
   }
 }