Add some new reftests which cover filter primitive subregion when scaled by page
zoom, or by hidpi. They should all be passing. I'm landing them to prevent
introducing regressions with upcoming patches (likely by me :) ).  Note that
page zoom applied to filter primitive subregion doesn't seem to be working in
the raster (non-hw) path. See http://crbug.com/335282.

R=fmalita

Review URL: https://codereview.chromium.org/136473005

git-svn-id: svn://svn.chromium.org/blink/trunk@165259 bbb929c8-8fbe-4397-9dbb-9b2b20218538
The anticlockwise parameter for CanvasRenderingContext2D.ellipse() is optional and has a default of false.

The spec reference is:
http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#dfnReturnLink-0

BUG=335124

Review URL: https://codereview.chromium.org/139173006

git-svn-id: svn://svn.chromium.org/blink/trunk@165260 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove redundant m_isItemCacheValid flag from LiveNodeListBase

We can simply do a null-check on the m_cachedItem pointer to check
if the cache is valid.

R=eseidel, esprehn
BUG=None

Review URL: https://codereview.chromium.org/136833002

git-svn-id: svn://svn.chromium.org/blink/trunk@165261 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add use counters for using Attrs as Nodes.

DOM4 makes Attr no longer be a subtype of Node. This adds a use
counter for passing Attr where Node is expected, or calling a method
declared on Node with an Attr.

BUG=305105

Review URL: https://codereview.chromium.org/127723002

git-svn-id: svn://svn.chromium.org/blink/trunk@165262 bbb929c8-8fbe-4397-9dbb-9b2b20218538