Implement DOMRect of geometry interfaces.

The DOMRect can represent a rectangle.

The specification:
http://dev.w3.org/fxtf/geometry/

Intent to Implement:
https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/V_bJNtOg0oM

BUG=388780

Review URL: https://codereview.chromium.org/403383002

git-svn-id: svn://svn.chromium.org/blink/trunk@178770 bbb929c8-8fbe-4397-9dbb-9b2b20218538
ASSERT in ScreenOrientationController::{un,}lock() if no m_client.

BUG=162827

Review URL: https://codereview.chromium.org/407923002

git-svn-id: svn://svn.chromium.org/blink/trunk@178771 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Fix a crash in V8AbstractEventListener::handleEvent

handleEvent() should check scriptState->contextIsEmpty() before doing anything that uses scriptState. This CL also adds a check for scriptState->executionContext() just in case (I'm not sure if it's really needed).

BUG=396104
TEST=I cannot reproduce the crash.

Review URL: https://codereview.chromium.org/411463006

git-svn-id: svn://svn.chromium.org/blink/trunk@178772 bbb929c8-8fbe-4397-9dbb-9b2b20218538