Introduce MaybeHandle to police exception checking in handlified code.

src/handles-inl.h

 // Copyright 2006-2008 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 22 matching lines @@
 #include "handles.h"
 #include "heap.h"
 #include "isolate.h"
 
 namespace v8 {
 namespace internal {
 
 template<typename T>
 Handle<T>::Handle(T* obj) {
   ASSERT(!obj->IsFailure());
-  location_ = HandleScope::CreateHandle(obj->GetIsolate(), obj);
+  this->location_ = HandleScope::CreateHandle(obj->GetIsolate(), obj);
 }
 
 
 template<typename T>
 Handle<T>::Handle(T* obj, Isolate* isolate) {
   ASSERT(!obj->IsFailure());
-  location_ = HandleScope::CreateHandle(isolate, obj);
+  this->location_ = HandleScope::CreateHandle(isolate, obj);
 }
 
 
 template <typename T>
 inline bool Handle<T>::is_identical_to(const Handle<T> o) const {
-  ASSERT(location_ == NULL || !(*location_)->IsFailure());
+  ASSERT(this->location_ == NULL || !(*this->location_)->IsFailure());
   // Dereferencing deferred handles to check object equality is safe.
   SLOW_ASSERT(
-      (location_ == NULL || IsDereferenceAllowed(NO_DEFERRED_CHECK)) &&
+      (this->location_ == NULL || IsDereferenceAllowed(NO_DEFERRED_CHECK)) &&
       (o.location_ == NULL || o.IsDereferenceAllowed(NO_DEFERRED_CHECK)));
-  if (location_ == o.location_) return true;
-  if (location_ == NULL || o.location_ == NULL) return false;
-  return *location_ == *o.location_;
+  if (this->location_ == o.location_) return true;
+  if (this->location_ == NULL || o.location_ == NULL) return false;
+  return *this->location_ == *o.location_;
 }
 
 
 template <typename T>
 inline T* Handle<T>::operator*() const {
-  ASSERT(location_ != NULL && !(*location_)->IsFailure());
+  ASSERT(this->location_ != NULL && !(*this->location_)->IsFailure());
   SLOW_ASSERT(IsDereferenceAllowed(INCLUDE_DEFERRED_CHECK));
-  return *BitCast<T**>(location_);
+  return *BitCast<T**>(this->location_);
 }
 
 template <typename T>
 inline T** Handle<T>::location() const {
-  ASSERT(location_ == NULL || !(*location_)->IsFailure());
-  SLOW_ASSERT(location_ == NULL ||
+  ASSERT(this->location_ == NULL || !(*this->location_)->IsFailure());
+  SLOW_ASSERT(this->location_ == NULL ||
               IsDereferenceAllowed(INCLUDE_DEFERRED_CHECK));
-  return location_;
+  return this->location_;
 }
 
 #ifdef DEBUG
 template <typename T>
 bool Handle<T>::IsDereferenceAllowed(DereferenceCheckMode mode) const {
-  ASSERT(location_ != NULL);
-  Object* object = *BitCast<T**>(location_);
+  ASSERT(this->location_ != NULL);
+  Object* object = *BitCast<T**>(this->location_);
   if (object->IsSmi()) return true;
   HeapObject* heap_object = HeapObject::cast(object);
   Heap* heap = heap_object->GetHeap();
-  Object** handle = reinterpret_cast<Object**>(location_);
+  Object** handle = reinterpret_cast<Object**>(this->location_);
   Object** roots_array_start = heap->roots_array_start();
   if (roots_array_start <= handle &&
       handle < roots_array_start + Heap::kStrongRootListLength &&
       heap->RootCanBeTreatedAsConstant(
         static_cast<Heap::RootListIndex>(handle - roots_array_start))) {
     return true;
   }
   if (!AllowHandleDereference::IsAllowed()) return false;
   if (mode == INCLUDE_DEFERRED_CHECK &&
       !AllowDeferredHandleDereference::IsAllowed()) {
@@ skipping 101 matching lines @@
   current->level = level_;
   ASSERT_EQ(current->next, current->limit);
   current->limit = limit_;
 }
 
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_HANDLES_INL_H_