Introduce builtin for Array.shift 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 1455 matching lines @@
     new_array->set(len+1, *value);
     new_array->set(len+2, *optimized);
     global_context()->set_special_function_table(*new_array);
   }
 }
 
 
 void Genesis::BuildSpecialFunctionTable() {
   HandleScope scope;
   Handle<JSObject> global = Handle<JSObject>(global_context()->global());
-  // Add special versions for Array.prototype.pop and push.
+  // Add special versions for some Array.prototype functions.
   Handle<JSFunction> function =
       Handle<JSFunction>(
           JSFunction::cast(global->GetProperty(Heap::Array_symbol())));
   Handle<JSObject> visible_prototype =
       Handle<JSObject>(JSObject::cast(function->prototype()));
-  // Remember to put push and pop on the hidden prototype if it's there.
-  Handle<JSObject> push_and_pop_prototype;
+  // Remember to put those specializations on the hidden prototype if present.
+  Handle<JSObject> special_prototype;
   Handle<Object> superproto(visible_prototype->GetPrototype());
   if (superproto->IsJSObject() &&
       JSObject::cast(*superproto)->map()->is_hidden_prototype()) {
-    push_and_pop_prototype = Handle<JSObject>::cast(superproto);
+    special_prototype = Handle<JSObject>::cast(superproto);
   } else {
-    push_and_pop_prototype = visible_prototype;
+    special_prototype = visible_prototype;
   }
-  AddSpecialFunction(push_and_pop_prototype, "pop",
+  AddSpecialFunction(special_prototype, "pop",
                      Handle<Code>(Builtins::builtin(Builtins::ArrayPop)));
-  AddSpecialFunction(push_and_pop_prototype, "push",
+  AddSpecialFunction(special_prototype, "push",
                      Handle<Code>(Builtins::builtin(Builtins::ArrayPush)));
+  AddSpecialFunction(special_prototype, "shift",
+                     Handle<Code>(Builtins::builtin(Builtins::ArrayShift)));
 }
 
 
 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