lockOrientation() fallback when the callback one isn't implemented.

Required to keep chromium working until it handles the callback method.

BUG=162827

Review URL: https://codereview.chromium.org/302703003

git-svn-id: svn://svn.chromium.org/blink/trunk@175128 bbb929c8-8fbe-4397-9dbb-9b2b20218538