Observed blank page when opened	'contain-paint.html' in chrome and attached 'contain-paint.mp4 'video is also blank.

l446240525@Could you please provide another sample html file with detailed description of actual and expected behavior screencast for further triaging the issue.

Thanks again for the great testcases.

I've modified this one a bit to make the bug easier to see:
http://jsbin.com/luvewe

@trchen, could you please fix this one? This is a new feature and we shouldn't accept
bugs in it.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1201e5870ce0bcbb9e31518fcbc2ac2635d07187

commit 1201e5870ce0bcbb9e31518fcbc2ac2635d07187
Author: trchen <trchen@chromium.org>
Date: Tue Jun 21 05:15:36 2016

Change CSS containment should invalidate layout

This CL does two things:
1. Changing CSS contain property requires a full layout. We can potentially
   do more fine-grained invalidation, but containment changes are expected to
   be rare.

2. Amend positioned descendants list update code to mirror the behavior of
   LayoutObject::canContainFixedPositionObjects().

BUG= 619864 

Review-Url: https://codereview.chromium.org/2072473003
Cr-Commit-Position: refs/heads/master@{#400899}

[add] https://crrev.com/1201e5870ce0bcbb9e31518fcbc2ac2635d07187/third_party/WebKit/LayoutTests/fast/css/containment/paint-containment-mutation-invalidates-layout-expected.html
[add] https://crrev.com/1201e5870ce0bcbb9e31518fcbc2ac2635d07187/third_party/WebKit/LayoutTests/fast/css/containment/paint-containment-mutation-invalidates-layout.html
[modify] https://crrev.com/1201e5870ce0bcbb9e31518fcbc2ac2635d07187/third_party/WebKit/Source/core/layout/LayoutBlock.cpp
[modify] https://crrev.com/1201e5870ce0bcbb9e31518fcbc2ac2635d07187/third_party/WebKit/Source/core/layout/LayoutObject.h
[modify] https://crrev.com/1201e5870ce0bcbb9e31518fcbc2ac2635d07187/third_party/WebKit/Source/core/style/ComputedStyle.cpp
[modify] https://crrev.com/1201e5870ce0bcbb9e31518fcbc2ac2635d07187/third_party/WebKit/Source/core/style/ComputedStyle.h