Heap-use-after-free in WebCore::Resource::checkNotify

Backed out of some overzealous shape-outside related postDestroy() changes in RenderObject.cpp (which I'd already backed out of in the WebKit version of the same code). This is a speculative fix.

BUG=362898

Review URL: https://codereview.chromium.org/232773014

git-svn-id: svn://svn.chromium.org/blink/trunk@171712 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Gardening: moving virtual/gpu/fast/canvas/canvas-composite-stroke-alpha.html

It was previously marked as Pass Timeout, but looking at the dashboard it
appears to just be slow on all platforms.

TBR=hayato@chromium.org
BUG=363029

Review URL: https://codereview.chromium.org/237963007

git-svn-id: svn://svn.chromium.org/blink/trunk@171713 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove some unnecessary settings null-checks from RenderLayerCompositor.

We only call these methods in the middle of layout or compositing update.
settings() only returns null on detached documents. We shouldn't
ever call layout or compositing update on a detached document.

Tested locally with an assert that we never have a null settings.
I don't think the assert is actually necessary to check in though.
If we started hitting this code with a null settings we'd just
have a crash at the next line of code anyways.

Also, cleaned up RenderLayerCompositor::updateAcceleratedCompositingSettings
a bit to not use local variables as much. This does mean we
call updateTriggers even if accelerated compositing is not enabled,
but that seems fine.

Review URL: https://codereview.chromium.org/239723003

git-svn-id: svn://svn.chromium.org/blink/trunk@171714 bbb929c8-8fbe-4397-9dbb-9b2b20218538