Remove StringImpl::m_substringBuffer

There aren't enough clients of this pointer to be worth keeping the feature in
StringImpl anymore. This CL paves the way to shrinking every StringImpl by one
pointer.

R=eseidel@chromium.org
BUG=262320

Review URL: https://codereview.chromium.org/19749009

git-svn-id: svn://svn.chromium.org/blink/trunk@154628 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Web Animations: Fix a bug where a null directed time was being passed to the timing function

Spec: See step 1 http://www.w3.org/TR/2013/WD-web-animations-20130625/#calculating-the-transformed-time
BUG=240653

Review URL: https://chromiumcodereview.appspot.com/19792010

git-svn-id: svn://svn.chromium.org/blink/trunk@154629 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Pass column as 4th argument to WorkerGlobalScope.onerror handler

As per the latest WebWorker specification, the WorkerGlobalScope.onerror
event handler should be given the column as fourth argument:
http://www.whatwg.org/specs/web-apps/current-work/multipage/workers.html#workerglobalscope
http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#onerroreventhandler

The behavior is consistent with IE10.

Note that ErrorEvent.column is not exposed yet because no other browser
implements it except IE10 which uses a different name ("colno").

BUG=262126
R=abarth@chromium.org, arv@chromium.org

Review URL: https://codereview.chromium.org/19693006

git-svn-id: svn://svn.chromium.org/blink/trunk@154630 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Supports mode should be reset in the same way as media query does.

When CharacterEndMediaQuery is found, parsing mode should be reset if the mode is supports mode.

BUG=257695

Review URL: https://chromiumcodereview.appspot.com/19624003

git-svn-id: svn://svn.chromium.org/blink/trunk@154631 bbb929c8-8fbe-4397-9dbb-9b2b20218538