Issue #1679 - Part 2: Some small issues to address buildability.

- Explicitly |this| the Asserts in Cell.as<>
- Unified deprot in regexp-error.h
- Convert RegExpShared* inner() to a reinterpret_cast because for SOME reason
  .as<> no longer works after the reimport (which is a static cast)

js/src/gc/Heap.h

@@ -280,13 +280,13 @@ struct Cell
 
     template<class T>
     inline T* as() {
-        MOZ_ASSERT(is<T>());
+        MOZ_ASSERT(this->is<T>());
         return static_cast<T*>(this);
     }
 
     template <class T>
     inline const T* as() const {
-        MOZ_ASSERT(is<T>());
+        MOZ_ASSERT(this->is<T>());
         return static_cast<const T*>(this);
     }
 

js/src/regexp/regexp-error.h

@@ -5,6 +5,7 @@
 #ifndef V8_REGEXP_REGEXP_ERROR_H_
 #define V8_REGEXP_REGEXP_ERROR_H_
 
+#include "regexp-shim.h"
 
 namespace v8 {
 namespace internal {

js/src/regexp/regexp-shim.h

@@ -957,7 +957,7 @@ class JSRegExp : public HeapObject {
 
 private:
   js::RegExpShared* inner() {
-    return value_.toGCThing()->as<js::RegExpShared>();
+    return reinterpret_cast<js::RegExpShared*>(value_.toGCThing());
   }
 };