Bug 743198 part 1 - Drop [Throws] of document.mozFullScreenElement. r=smaug

This method actually never throws. IsFullScreenDoc() simply checks
whether GetFullScreenElement() returns nullptr, which means if that
method returns true, the "!el" check would never fail.

--HG--
extra : source : f32a1aeb6835fd4b4c47ef3abe6b9d7366ae4f07

dom/base/nsDocument.cpp

@@ -11955,30 +11955,12 @@ nsDocument::ApplyFullscreen(const FullscreenRequest& aRequest)
 NS_IMETHODIMP
 nsDocument::GetMozFullScreenElement(nsIDOMElement **aFullScreenElement)
 {
-  ErrorResult rv;
-  Element* el = GetMozFullScreenElement(rv);
-  if (rv.Failed()) {
-    return rv.StealNSResult();
-  }
+  Element* el = GetMozFullScreenElement();
   nsCOMPtr<nsIDOMElement> retval = do_QueryInterface(el);
   retval.forget(aFullScreenElement);
   return NS_OK;
 }
 
-Element*
-nsDocument::GetMozFullScreenElement(ErrorResult& rv)
-{
-  if (IsFullScreenDoc()) {
-    // Must have a full-screen element while in full-screen mode.
-    Element* el = GetFullScreenElement();
-    if (!el) {
-      rv.Throw(NS_ERROR_UNEXPECTED);
-    }
-    return el;
-  }
-  return nullptr;
-}
-
 Element*
 nsDocument::GetFullScreenElement()
 {

dom/base/nsDocument.h

@@ -1262,7 +1262,7 @@ public:
 
   // DOM-exposed fullscreen API
   virtual bool MozFullScreenEnabled() override;
-  virtual Element* GetMozFullScreenElement(mozilla::ErrorResult& rv) override;
+  Element* GetMozFullScreenElement() override { return GetFullScreenElement(); }
 
   void RequestPointerLock(Element* aElement) override;
   bool ShouldLockPointer(Element* aElement, Element* aCurrentLock,

dom/base/nsIDocument.h

@@ -2504,7 +2504,7 @@ public:
   nsIURI* GetDocumentURIObject() const;
   // Not const because all the full-screen goop is not const
   virtual bool MozFullScreenEnabled() = 0;
-  virtual Element* GetMozFullScreenElement(mozilla::ErrorResult& rv) = 0;
+  virtual Element* GetMozFullScreenElement() = 0;
   bool MozFullScreen()
   {
     return IsFullScreenDoc();

dom/webidl/Document.webidl

@@ -225,7 +225,6 @@ partial interface Document {
   // Note: Per spec the 'S' in these two is lowercase, but the "Moz"
   // versions hve it uppercase.
   readonly attribute boolean mozFullScreenEnabled;
-  [Throws]
   readonly attribute Element? mozFullScreenElement;
 
   //(Renamed?)void exitFullscreen();