Add support for 'allow-orientation-lock' sandboxing directive

Add support for 'allow-orientation-lock' sandboxing directive when parsing
sandboxing directives:
https://w3c.github.io/screen-orientation/#dfn-sandboxed-orientation-lock-browsing-context-flag

Also throw an SecurityError DOMException if screen.lockOrientation() is called
on a Document whose active sandboxing flag set has the sandboxed orientation
lock browsing context flag set, as per the latest Screen Orientation API: 
https://w3c.github.io/screen-orientation/#dfn-apply-an-orientation-lock

R=abarth@chromium.org
BUG=162827
TEST=screen_orientation/lockOrientation-sandboxed-iframe.html

Review URL: https://codereview.chromium.org/272213002

git-svn-id: svn://svn.chromium.org/blink/trunk@173806 bbb929c8-8fbe-4397-9dbb-9b2b20218538