--- a/content/base/src/nsGenericElement.h
+++ b/content/base/src/nsGenericElement.h
@@ -1046,18 +1046,18 @@ nsresult                                
  * SetAttr methods.  We use the 5-argument form of SetAttr, because
  * some consumers only implement that one, hiding superclass
  * 4-argument forms.
  */
 #define NS_IMPL_STRING_ATTR(_class, _method, _atom)                     \
   NS_IMETHODIMP                                                         \
   _class::Get##_method(nsAString& aValue)                               \
   {                                                                     \
-    /* XXX Invalid cast of bool to nsresult (bug 778104) */             \
-    return (nsresult)GetAttr(kNameSpaceID_None, nsGkAtoms::_atom, aValue); \
+    GetAttr(kNameSpaceID_None, nsGkAtoms::_atom, aValue);               \
+    return NS_OK;                                                       \
   }                                                                     \
   NS_IMETHODIMP                                                         \
   _class::Set##_method(const nsAString& aValue)                         \
   {                                                                     \
     return SetAttr(kNameSpaceID_None, nsGkAtoms::_atom, nullptr, aValue, true); \
   }
 
 /**