Allocate arguments object on-demand instead of at function entry....

src/runtime.js

 // 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 373 matching lines @@
     throw %MakeTypeError('called_non_callable', [typeof callee]);
   }
 
   var parameters = %NewArguments(delegate);
   return delegate.apply(callee, parameters);
 }
 
 
 function APPLY_PREPARE(args) {
   var length;
-  // First check whether length is a positive Smi and args is an array.  This is the
-  // fast case.  If this fails, we do the slow case that takes care of more eventualities
+  // First check whether length is a positive Smi and args is an
+  // array. This is the fast case. If this fails, we do the slow case
+  // that takes care of more eventualities.
   if (%_IsArray(args)) {
     length = args.length;
     if (%_IsSmi(length) && length >= 0 && length < 0x800000 && IS_FUNCTION(this)) {
       return length;
     }
   }
 
   length = (args == null) ? 0 : %ToUint32(args.length);
 
   // We can handle any number of apply arguments if the stack is
@@ skipping 172 matching lines @@
   throw %MakeTypeError('cannot_convert_to_primitive', []);
 }
 
 
 // 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 essiential that the
 // boilerplate gets the right prototype.
 %FunctionSetPrototype($Array, new $Array(0));