Revert of Disable the HTMLVideoElement-specific prefixed fullscreen API (2nd...

Revert of Disable the HTMLVideoElement-specific prefixed fullscreen API (2nd attempt) (https://codereview.chromium.org/251873002/)

Reason for revert:
Wait with removal until the unprefixed Fullscreen API has been shipped.

Original issue's description:
> Disable the HTMLVideoElement-specific prefixed fullscreen API (2nd attempt)
> 
> BUG=346236
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=172693

Review URL: https://codereview.chromium.org/328303003

git-svn-id: svn://svn.chromium.org/blink/trunk@176144 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/platform/RuntimeEnabledFeatures.in

@@ -22,7 +22,7 @@ Beacon status=experimental
 
 // This feature is deprecated and we are evangalizing affected sites.
 // See https://crbug.com/346236 for current status.
-PrefixedVideoFullscreen status=test
+PrefixedVideoFullscreen status=stable
 
 // Enable bleeding-edge code to make Blink draw content faster.
 // The changes enabled behind this flag are very likely to break lots of content.