Tweak the TurboFan pipeline for stub compilation.

src/runtime.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This files contains runtime support implemented in JavaScript.
 
 // CAUTION: Some of the functions specified in this file are called
 // directly from compiled code. These are the functions with names in
 // ALL CAPS. The compiled code passes the first argument in 'this'.
 
@@ skipping 676 matching lines @@
   return i;
 }
 
 
 // NOTE: Setting the prototype for Array must take place as early as
 // possible due to code generation for array literals.  When
 // generating code for a array literal a boilerplate array is created
 // that is cloned when running the code.  It is essential that the
 // boilerplate gets the right prototype.
 %FunctionSetPrototype($Array, new $Array(0));
+
+
+/* -----------------------------------------------
+   - - -   J a v a S c r i p t   S t u b s   - - -
+   -----------------------------------------------
+*/
+
+function STRING_LENGTH_STUB(name) {
+  var receiver = this;  // implicit first parameter
+  return %_StringGetLength(%_JSValueGetValue(receiver));
+}