Sync HTML element interfaces S-V with the spec

Source/core/html/HTMLVideoElement.idl

Index: Source/core/html/HTMLVideoElement.idl
diff --git a/Source/core/html/HTMLVideoElement.idl b/Source/core/html/HTMLVideoElement.idl
index 04f6d1bcb955134a617b0eb256cf126138225410..5989128777fd69af31fe134522b108fcae388b22 100644
--- a/Source/core/html/HTMLVideoElement.idl
+++ b/Source/core/html/HTMLVideoElement.idl
@@ -23,6 +23,8 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+// https://html.spec.whatwg.org/#the-video-element
+
 [
     RuntimeEnabled=Media
 ] interface HTMLVideoElement : HTMLMediaElement {
@@ -32,6 +34,7 @@
     readonly attribute unsigned long videoHeight;
     [Reflect, URL] attribute DOMString poster;
 
+    // Non-standard APIs
     [RuntimeEnabled=PrefixedVideoFullscreen, DeprecateAs=PrefixedVideoSupportsFullscreen] readonly attribute boolean webkitSupportsFullscreen;
     [RuntimeEnabled=PrefixedVideoFullscreen, DeprecateAs=PrefixedVideoDisplayingFullscreen] readonly attribute boolean webkitDisplayingFullscreen;