Bug 903425 - Update TextTrackCue::Vertical to be a DirectionSetting enum. r=rillian

Following up with the changes made in http://dev.w3.org/html5/webvtt/#dfn-dom-vttcue-vertical, this patch comes to create a new enum to validate and control the possible values for TextTrackCue::Vertical. Throwing behavior was removed for spec conformance.

content/media/TextTrackCue.cpp

@@ -37,6 +37,7 @@ TextTrackCue::SetDefaultCueSettings()
   mSnapToLines = true;
   mLine = WEBVTT_AUTO;
   mAlign = TextTrackCueAlign::Middle;
+  mVertical = DirectionSetting::_empty;
 }
 
 TextTrackCue::TextTrackCue(nsISupports* aGlobal,

content/media/TextTrackCue.h

@@ -120,21 +120,16 @@ public:
     CueChanged();
   }
 
-  void GetVertical(nsAString& aVertical)
+  DirectionSetting Vertical() const
   {
-    aVertical = mVertical;
+    return mVertical;
   }
 
-  void SetVertical(const nsAString& aVertical, ErrorResult& aRv)
+  void SetVertical(const DirectionSetting& aVertical)
   {
     if (mVertical == aVertical)
       return;
 
-    if (!aVertical.EqualsLiteral("rl") && !aVertical.EqualsLiteral("lr") && !aVertical.IsEmpty()){
-      aRv.Throw(NS_ERROR_DOM_SYNTAX_ERR);
-      return;
-    }
-
     mReset = true;
     mVertical = aVertical;
     CueChanged();
@@ -344,7 +339,7 @@ private:
   int32_t mSize;
   bool mPauseOnExit;
   bool mSnapToLines;
-  nsString mVertical;
+  DirectionSetting mVertical;
   int mLine;
   TextTrackCueAlign mAlign;
 

dom/webidl/VTTCue.webidl

@@ -19,6 +19,12 @@ enum TextTrackCueAlign {
   "right"
 };
 
+enum DirectionSetting {
+  "",
+  "rl",
+  "lr"
+};
+
 [Constructor(double startTime, double endTime, DOMString text),
  Pref="media.webvtt.enabled"]
 interface VTTCue : EventTarget {
@@ -28,8 +34,7 @@ interface VTTCue : EventTarget {
   attribute double startTime;
   attribute double endTime;
   attribute boolean pauseOnExit;
-  [SetterThrows]
-  attribute DOMString vertical;
+  attribute DirectionSetting vertical;
   attribute boolean snapToLines;
   // XXXhumph: https://www.w3.org/Bugs/Public/show_bug.cgi?id=20651
   // attribute (long or AutoKeyword) line;