DEFINE_CSS_VALUE_TYPE_CASTS starts to use DEFINE_TYPE_CASTS

DEFINE_CSS_VALUE_TYPE_CASTS starts to use DEFINE_TYPE_CASTS so that it is more flexible.
Under this change, unusual CSS child values also will be able to use the DEFINE_CSS_VALUE_TYPE_CASTS.

BUG=N/A

Review URL: https://codereview.chromium.org/30963002

git-svn-id: svn://svn.chromium.org/blink/trunk@160030 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add UseCounters for prefixed HTMLVideoElement APIs

Count the *Fullscreen and *FullScreen calls separately, since it's likely
that the later are less common and could potentially be dropped first.

BUG=309364

Review URL: https://codereview.chromium.org/31203002

git-svn-id: svn://svn.chromium.org/blink/trunk@160031 bbb929c8-8fbe-4397-9dbb-9b2b20218538