Bug 1761536 - Part 2: Replace nsTArray::elem_type with value_type, r=mccr8

There weren't that many uses of the existing typedef, so it seemed like
it might be worthwhile to just replace all uses of the previous typedef
with the stl-like one.

Differential Revision: https://phabricator.services.mozilla.com/D142705

dom/canvas/QueueParamTraits.h

@@ -488,7 +488,7 @@ struct QueueParamTraits<nsString> : public QueueParamTraits<nsAString> {
 
 template <typename NSTArrayType,
           bool =
-              IsTriviallySerializable<typename NSTArrayType::elem_type>::value>
+              IsTriviallySerializable<typename NSTArrayType::value_type>::value>
 struct NSArrayQueueParamTraits;
 
 // For ElementTypes that are !IsTriviallySerializable