Remove dead code from our JS builtin-code in math.js.

$random is never used within our JS builtin code.
Review URL: https://chromiumcodereview.appspot.com/10166003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11400 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/math.js

@@ -30,7 +30,6 @@
 // has the added benefit that the code in this file is isolated from
 // changes to these properties.
 var $floor = MathFloor;
-var $random = MathRandom;
 var $abs = MathAbs;
 
 // Instance class name can only be set on functions. That is the only