Introduce builtin for Array.unshift function.

src/bootstrapper.cc

 // 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 1476 matching lines @@
     special_prototype = Handle<JSObject>::cast(superproto);
   } else {
     special_prototype = visible_prototype;
   }
   AddSpecialFunction(special_prototype, "pop",
                      Handle<Code>(Builtins::builtin(Builtins::ArrayPop)));
   AddSpecialFunction(special_prototype, "push",
                      Handle<Code>(Builtins::builtin(Builtins::ArrayPush)));
   AddSpecialFunction(special_prototype, "shift",
                      Handle<Code>(Builtins::builtin(Builtins::ArrayShift)));
+  AddSpecialFunction(special_prototype, "unshift",
+                     Handle<Code>(Builtins::builtin(Builtins::ArrayUnshift)));
 }
 
 
 Genesis::Genesis(Handle<Object> global_object,
                  v8::Handle<v8::ObjectTemplate> global_template,
                  v8::ExtensionConfiguration* extensions) {
   // Link this genesis object into the stacked genesis chain. This
   // must be done before any early exits because the destructor
   // will always do unlinking.
   previous_ = current_;
@@ skipping 65 matching lines @@
 }
 
 
 // Restore statics that are thread local.
 char* Genesis::RestoreState(char* from) {
   current_ = *reinterpret_cast<Genesis**>(from);
   return from + sizeof(current_);
 }
 
 } }  // namespace v8::internal