[S.P.] Invalidate the document element for view background when needed

LayoutTests/fast/repaint/resources/window-resize-repaint.js

 var testSizes = [
     { width: 200, height: 200 }, // initial size
     { width: 200, height: 300 }, // height increase
     { width: 300, height: 300 }, // width increase
     { width: 300, height: 250 }, // height decrease
     { width: 250, height: 250 }  // width decrease
     // Tests can add more testSizes.
 ];
 
 var sizeIndex = 0;
@@ skipping 13 matching lines @@
 
     window.onload = function() {
         window.resizeTo(testSizes[0].width, testSizes[0].height);
 
         var repaintRects = "";
         for (sizeIndex = 1; sizeIndex < testSizes.length; ++sizeIndex) {
             document.body.offsetTop;
             internals.startTrackingRepaints(document);
             repaintTest();
             document.body.offsetTop;
-            repaintRects += internals.layerTreeAsText(document, window.internals.LAYER_TREE_INCLUDES_REPAINT_RECTS);
+            repaintRects += internals.layerTreeAsText(document, window.internals.LAYER_TREE_INCLUDES_REPAINT_RECTS | window.internals.LAYER_TREE_INCLUDES_PAINT_INVALIDATION_OBJECTS);

[chrishtr, 2015/03/18 19:30:05]

But it doesn't affect any tests?

[Xianzhu, 2015/03/18 19:36:28]

Yes. I'm running trybots to show the expectation changes in the results, and add
NeedsRebaseline in the next patch set.

             internals.stopTrackingRepaints(document);
         }
         testRunner.setCustomTextOutput(repaintRects);
     }
 }