Move some heap verification code in under the --verify-heap flag to speed

src/heap-inl.h

 // Copyright 2011 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 572 matching lines @@
 
 void ExternalStringTable::AddOldString(String* string) {
   ASSERT(string->IsExternalString());
   ASSERT(!heap_->InNewSpace(string));
   old_space_strings_.Add(string);
 }
 
 
 void ExternalStringTable::ShrinkNewStrings(int position) {
   new_space_strings_.Rewind(position);
-  Verify();
+  if (FLAG_verify_heap) {
+    Verify();
+  }
 }
 
 
 void Heap::ClearInstanceofCache() {
   set_instanceof_cache_function(the_hole_value());
 }
 
 
 Object* Heap::ToBoolean(bool condition) {
   return condition ? true_value() : false_value();
@@ skipping 70 matching lines @@
 
 
 Heap* _inline_get_heap_() {
   return HEAP;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_INL_H_