Remove the allowfullscreen exemption for the video-specific fullscreen API (reland)

Source/core/frame/UseCounter.cpp

Index: Source/core/frame/UseCounter.cpp
diff --git a/Source/core/frame/UseCounter.cpp b/Source/core/frame/UseCounter.cpp
index e89ae9f000be7fbb390caaf961a2d22e4e1a357d..e897d5d4cc34784d646d652a869dcbe0ddf759eb 100644
--- a/Source/core/frame/UseCounter.cpp
+++ b/Source/core/frame/UseCounter.cpp
@@ -922,9 +922,6 @@ String UseCounter::deprecationMessage(Feature feature)
     case PrefixedMouseEventMovementY:
         return replacedBy("webkitMovementY", "movementY");
 
-    case VideoFullscreenAllowedExemption:
-        return "Entering fullscreen in an <iframe> with no allowfullscreen attribute is deprecated and will stop working in M46, around October 2015. Please use the allowfullscreen attribute.";
-
     case SVGSMILElementInDocument:
     case SVGSMILAnimationInImageRegardlessOfCache:
         return "SVG's SMIL animations (<animate>, <set>, etc.) are deprecated and will be removed. Please use CSS animations or Web animations instead.";