Make image decoders notify bitmaps of pixel changes.

ImageFrame now has a flag to indicate that its pixels were changed, but the SkBitmaps have not yet been notified of the change.
ImageDecoders (JPEG, PNG, GIF, WebP) set this flag when they changed the pixels.
The bitmaps are notified if pixels changed, before a frame is returned from frameBufferAtIndex.

This will make SkPixelRef generationIDs unique for frames
of animated images and for progressive decoded images.

R=hclam@chromium.org,reveman@chromium.org,reed@chromium.org,enne@chromium.org
BUG=307689

Review URL: https://codereview.chromium.org/75303004

git-svn-id: svn://svn.chromium.org/blink/trunk@162410 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove viewport rule special casing from StyleResolver.

As best I can tell, this was only needed because the tests didn't
correctly force a style recalc before measuring viewport sizes.
The tests used to synchronously update the stylesheets when they
were modified, with r162187 they do so at recalc time.

The tests in question are the css3/device-adapt tests.
Now have the Internals API force a recalc and update.

BUG=308796

Review URL: https://codereview.chromium.org/76623003

git-svn-id: svn://svn.chromium.org/blink/trunk@162411 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Mark premultiplyapha-test.html as flaky on windows

BUG=321787
TEST=
TBR=kbr@chromium.org

Review URL: https://codereview.chromium.org/77763008

git-svn-id: svn://svn.chromium.org/blink/trunk@162413 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Mark fast/frames/sandboxed-iframe-navigation-windowopen.html as flaky on windows

It times out from time to time

BUG=321793
TEST=
TBR=abarth@chromium.org

Review URL: https://codereview.chromium.org/79293003

git-svn-id: svn://svn.chromium.org/blink/trunk@162414 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Introduce RenderLayerStackingNodeReverseIterator

This enables us to move all callers of the z-order and
normal flow lists accessors to the iterator pattern.

As part of this change, made the lists accessors private to
force people to use the iterators. The only exception to this
is RenderTreeAsText that needs to know the lists size.

BUG=302120

Review URL: https://codereview.chromium.org/76703003

git-svn-id: svn://svn.chromium.org/blink/trunk@162416 bbb929c8-8fbe-4397-9dbb-9b2b20218538