[SVG] merge SVGAnimatedNewPropertyAnimator to SVGAnimatedTypeAnimator

After the new svg properties transition, SVGAnimatedNewPropertyAnimator is the only SVGAnimatedTypeAnimator.
This CL merges the SVGAnimatedNewPropertyAnimator functionality to SVGAnimatedTypeAnimator, and removes SVGAnimatorFactory.

BUG=349370

Review URL: https://codereview.chromium.org/194623002

git-svn-id: svn://svn.chromium.org/blink/trunk@169010 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove V8PerIsolateData::isMainThread

Now it's unused.

BUG=341032

Review URL: https://codereview.chromium.org/196473004

git-svn-id: svn://svn.chromium.org/blink/trunk@169011 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: Fix wrong is-array-like detection when logging in console.

1) Functions should not be logged as array-like objects.
2) Log DOMTokenList as array in console, like we already do for HTMLCollection and NodeList.

BUG=350644
R=pfeldman

Review URL: https://codereview.chromium.org/197073004

git-svn-id: svn://svn.chromium.org/blink/trunk@169012 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Implement will-change-based GPU rasterization hint

This uses an element's will-change value to determine
whether it should have a GPU rasterization hint, and
uses a newly-added 
acceleratedCompositingForGpuRasterizationHintEnabled
setting to determine whether to create composited layers
for elements that have a GPU rasterization hint.

will-change is currently behind a runtime flag.

Intent-to-implement:
https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/M62y2nKZ-gE

Spec: http://tabatkins.github.io/specs/css-will-change/

BUG=313532

Review URL: https://codereview.chromium.org/183103007

git-svn-id: svn://svn.chromium.org/blink/trunk@169013 bbb929c8-8fbe-4397-9dbb-9b2b20218538