shape-outside does not properly handle the container and the float having different writing modes

The margin box offset needs to be computed based on the writing mode
of the container, not the writihg mode of the float itself. This
patch makes that happen.

Review URL: https://codereview.chromium.org/27241002

git-svn-id: svn://svn.chromium.org/blink/trunk@159644 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Separate Custom Elements base element queue from the processing stack.

Custom Element callback processing is complicated by HTML Imports: The
Base Element Queue (BEQ) must not run ahead of loading imports so that
the author can rely on script blocks in the import having taken
effect.

This is a refactoring to separate the BEQ from the processing
stack. There's no change in behavior yet. In a follow-up change the
BEQ will maintain elements in import tree order.

BUG=234509

Review URL: https://codereview.chromium.org/26791002

git-svn-id: svn://svn.chromium.org/blink/trunk@159645 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Web Animations CSS: Fix crashing background-size

Test crashing due to merge fail between patches:
https://codereview.chromium.org/26259003/
https://codereview.chromium.org/26355006/

TBR=dstockwell

Review URL: https://codereview.chromium.org/27274003

git-svn-id: svn://svn.chromium.org/blink/trunk@159646 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Rename ScriptExecutionContext to ExecutionContext.

This is reland of r159430 which was reverted as a part of r159599.
It was reverted just because of the dependency and this change itself
has no breakage.

TBR=jochen
BUG=305497

Review URL: https://codereview.chromium.org/26872003

git-svn-id: svn://svn.chromium.org/blink/trunk@159647 bbb929c8-8fbe-4397-9dbb-9b2b20218538