Back out 022bc808586b (bug 845147) on suspicion of causing frequent intermittent oranges for list-simple-1.html by busting its reference case

image/src/RasterImage.cpp

@@ -2765,10 +2765,7 @@ RasterImage::RequestDecode()
 NS_IMETHODIMP
 RasterImage::StartDecoding()
 {
-  // Here we are explicitly trading off flashing for responsiveness in the case
-  // that we're redecoding an image (see bug 845147).
-  return RequestDecodeCore(mHasBeenDecoded ?
-    SYNCHRONOUS_NOTIFY : SYNCHRONOUS_NOTIFY_AND_SOME_DECODE);
+  return RequestDecodeCore(SYNCHRONOUS_NOTIFY_AND_SOME_DECODE);
 }