Introduce MaybeHandle to police exception checking in handlified code.

src/handles-inl.h

Index: src/handles-inl.h
diff --git a/src/handles-inl.h b/src/handles-inl.h
index 19a02cca9ae9b32871dffd6258db0bcec339ea49..612024a67b60d2bbfca711fd39170923f83c6438 100644
--- a/src/handles-inl.h
+++ b/src/handles-inl.h
@@ -40,54 +40,54 @@ 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 &&