Introduce MaybeHandle to police exception checking in handlified code.

src/api.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 300 matching lines @@
 
  private:
   static void ReportApiFailure(const char* location, const char* message);
 };
 
 
 template <class T>
 v8::internal::Handle<T> v8::internal::Handle<T>::EscapeFrom(
     v8::EscapableHandleScope* scope) {
   v8::internal::Handle<T> handle;
-  if (!is_null()) {
-    handle = *this;
-  }
+  if (!this->is_null()) handle = *this;
   return Utils::OpenHandle(*scope->Escape(Utils::ToLocal(handle)), true);
 }
 
 
 template <class T>
 inline T* ToApi(v8::internal::Handle<v8::internal::Object> obj) {
   return reinterpret_cast<T*>(obj.location());
 }
 
 template <class T>
@@ skipping 375 matching lines @@
     stress_type_ = stress_type;
   }
 
  private:
   static v8::Testing::StressType stress_type_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_API_H_