Bug 1449806: Merge {Servo,Generic}SpecifiedValues into MappedDeclarations. r=xidorn

The idea would be that this header is only included in cpp files, thus it's ok
to include ServoBindings, etc.

MozReview-Commit-ID: EgQEsR0cZd4

dom/html/HTMLTableColElement.h

@@ -89,7 +89,7 @@ protected:
 
 private:
   static void MapAttributesIntoRule(const nsMappedAttributes* aAttributes,
-                                    GenericSpecifiedValues* aGenericData);
+                                    MappedDeclarations&);
 };
 
 } // namespace dom