Assert external strings in external string table. Remove TODOs.

src/heap-inl.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 700 matching lines @@
   }
 }
 
 
 // Verify() is inline to avoid ifdef-s around its calls in release
 // mode.
 void ExternalStringTable::Verify() {
 #ifdef DEBUG
   for (int i = 0; i < new_space_strings_.length(); ++i) {
     Object* obj = Object::cast(new_space_strings_[i]);
-    // TODO(yangguo): check that the object is indeed an external string.
     ASSERT(heap_->InNewSpace(obj));
     ASSERT(obj != HEAP->the_hole_value());
   }
   for (int i = 0; i < old_space_strings_.length(); ++i) {
     Object* obj = Object::cast(old_space_strings_[i]);
-    // TODO(yangguo): check that the object is indeed an external string.
     ASSERT(!heap_->InNewSpace(obj));
     ASSERT(obj != HEAP->the_hole_value());
   }
 #endif
 }
 
 
 void ExternalStringTable::AddOldString(String* string) {
   ASSERT(string->IsExternalString());
   ASSERT(!heap_->InNewSpace(string));
@@ skipping 145 matching lines @@
 DisallowAllocationFailure::~DisallowAllocationFailure() {
 #ifdef DEBUG
   HEAP->disallow_allocation_failure_ = old_state_;
 #endif
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_INL_H_