Add a public API for using an empty sring.

src/api.cc

 // Copyright 2007-2008 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 2454 matching lines @@
 
 Local<External> v8::External::New(void* data) {
   STATIC_ASSERT(sizeof(data) == sizeof(i::Address));
   LOG_API("External::New");
   EnsureInitialized("v8::External::New()");
   i::Handle<i::Proxy> obj = i::Factory::NewProxy(static_cast<i::Address>(data));
   return Utils::ToLocal(obj);
 }
 
 
+Local<String> v8::String::Empty() {
+  EnsureInitialized("v8::String::Empty()");
+  LOG_API("String::Empty()");
+  return Utils::ToLocal(i::Factory::empty_symbol());
+}
+
+
 Local<String> v8::String::New(const char* data, int length) {
   EnsureInitialized("v8::String::New()");
   LOG_API("String::New(char)");
+  if (length == 0) return Empty();
   if (length == -1) length = strlen(data);
   i::Handle<i::String> result =
       i::Factory::NewStringFromUtf8(i::Vector<const char>(data, length));
   return Utils::ToLocal(result);
 }
 
 
 Local<String> v8::String::NewUndetectable(const char* data, int length) {
   EnsureInitialized("v8::String::NewUndetectable()");
   LOG_API("String::NewUndetectable(char)");
   if (length == -1) length = strlen(data);
   i::Handle<i::String> result =
       i::Factory::NewStringFromUtf8(i::Vector<const char>(data, length));
   result->MarkAsUndetectable();
   return Utils::ToLocal(result);
 }
 
 
 static int TwoByteStringLength(const uint16_t* data) {
   int length = 0;
   while (data[length] != '\0') length++;
   return length;
 }
 
 
 Local<String> v8::String::New(const uint16_t* data, int length) {
   EnsureInitialized("v8::String::New()");
   LOG_API("String::New(uint16_)");
+  if (length == 0) return Empty();
   if (length == -1) length = TwoByteStringLength(data);
   i::Handle<i::String> result =
       i::Factory::NewStringFromTwoByte(i::Vector<const uint16_t>(data, length));
   return Utils::ToLocal(result);
 }
 
 
 Local<String> v8::String::NewUndetectable(const uint16_t* data, int length) {
   EnsureInitialized("v8::String::NewUndetectable()");
   LOG_API("String::NewUndetectable(uint16_)");
@@ skipping 628 matching lines @@
       reinterpret_cast<HandleScopeImplementer*>(storage);
   List<void**>* blocks_of_archived_thread = thread_local->Blocks();
   v8::ImplementationUtilities::HandleScopeData* handle_data_of_archived_thread =
       &thread_local->handle_scope_data_;
   Iterate(v, blocks_of_archived_thread, handle_data_of_archived_thread);
 
   return storage + ArchiveSpacePerThread();
 }
 
 } }  // namespace v8::internal