Bug 1325878: Don't hardode nsMediaList in dom::StyleSheet. r=xidorn

MozReview-Commit-ID: IynF1NFUSLf
Signed-off-by: Emilio Cobos Álvarez <emilio@crisal.io>

layout/style/MediaList.h

@@ -41,11 +41,18 @@ public:
   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(MediaList)
 
   /**
-   * Creates a MediaList backed by the StyleBackendType of the document.
+   * Creates a MediaList backed by the given StyleBackendType.
    */
   static already_AddRefed<MediaList> Create(StyleBackendType,
                                             const nsAString& aMedia);
 
+  /**
+   * Creates a MediaList backed by the given StyleBackendType.
+   */
+  static already_AddRefed<MediaList> Create(StyleBackendType aBackendType) {
+    return Create(aBackendType, nsString());
+  }
+
   /**
    * Creates a MediaList backed by the StyleBackendType of the document.
    */

layout/style/StyleSheet.cpp

@@ -14,7 +14,6 @@
 #include "mozilla/CSSStyleSheet.h"
 
 #include "mozAutoDocUpdate.h"
-#include "nsMediaList.h"
 #include "NullPrincipal.h"
 
 namespace mozilla {
@@ -692,7 +691,7 @@ dom::MediaList*
 StyleSheet::Media()
 {
   if (!mMedia) {
-    mMedia = new nsMediaList();
+    mMedia = dom::MediaList::Create(mType);
     mMedia->SetStyleSheet(this);
   }