Revert "Ensure that if FrameView::isScrollable() is false, the assoc WebLayer is, too."

This change reverts r164629; this is a speculative revert to see
if this change broke some Android unit tests. It looks like
this change also broke some layout tests. See comments on the bug
for more details.

TBR=vollick@chromium.org, adamk@chromium.org
BUG=328672

Review URL: https://codereview.chromium.org/127303003

git-svn-id: svn://svn.chromium.org/blink/trunk@164653 bbb929c8-8fbe-4397-9dbb-9b2b20218538
PartitionAlloc: move seedPage and similar items to a global variable.

(This is a part of re-landing the reviewed but reverted
https://codereview.chromium.org/105503009/
in incremental pieces.)

TBR=tsepez@chromium.org
BUG=327095

Review URL: https://codereview.chromium.org/127323002

git-svn-id: svn://svn.chromium.org/blink/trunk@164654 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Revert "Completely removed the Extensions3D class"

This reverts r164652, which broke the Android build (I think).

TBR=bajones@chromium.org
BUG=326382

Review URL: https://codereview.chromium.org/126823005

git-svn-id: svn://svn.chromium.org/blink/trunk@164655 bbb929c8-8fbe-4397-9dbb-9b2b20218538