Web Animations: Relax tolerance in play-state-initially-paused.html

This test uses setTimeout() to unpause the animations, so can't use DRT's
animation pause API and is therefore susceptible to flakiness.

BUG=321841, 322272
R=dstockwell

Review URL: https://codereview.chromium.org/90263002

git-svn-id: svn://svn.chromium.org/blink/trunk@162747 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Moving WebCore::BlendMode to blink::WebBlendMode

Blend modes are required in the public interface for passing blending
parameters to the compositor.

Review URL: https://codereview.chromium.org/90313002

git-svn-id: svn://svn.chromium.org/blink/trunk@162748 bbb929c8-8fbe-4397-9dbb-9b2b20218538