crbug.com/469678: We should fire an image load event even if the image is the last one we loaded successfully.

In this test we load an image. Then we make a null request (img.src='') which should clear down the image before we attempt to load the same image again.

PASS successfullyParsed is true

TEST COMPLETE
Image onload event fired for green.jpg
Image onload event fired for green.jpg
PASS