Implement xorshift128+ for Math.random.

src/js/prologue.js

 // Copyright 2015 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.
 
 (function(global, utils, extrasUtils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
@@ skipping 227 matching lines @@
   %CheckIsBootstrapping();
   %ExportExperimentalFromRuntime(exports_container);
   for ( ; !IS_UNDEFINED(imports); imports = imports.next) {
     imports(exports_container);
   }
   for ( ; !IS_UNDEFINED(imports_from_experimental);
           imports_from_experimental = imports_from_experimental.next) {
     imports_from_experimental(exports_container);
   }
 
-  utils.InitializeRNG();
-  utils.InitializeRNG = UNDEFINED;
   utils.CreateDoubleResultArray();
   utils.CreateDoubleResultArray = UNDEFINED;
 
   utils.Export = UNDEFINED;
   utils.PostDebug = UNDEFINED;
   utils.PostExperimentals = UNDEFINED;
   typed_array_setup = UNDEFINED;
 }
 
 
 function PostDebug(utils) {
   for ( ; !IS_UNDEFINED(imports); imports = imports.next) {
     imports(exports_container);
   }
 
-  utils.InitializeRNG();
-  utils.InitializeRNG = UNDEFINED;
   utils.CreateDoubleResultArray();
   utils.CreateDoubleResultArray = UNDEFINED;
 
   exports_container = UNDEFINED;
 
   utils.Export = UNDEFINED;
   utils.Import = UNDEFINED;
   utils.ImportNow = UNDEFINED;
   utils.PostDebug = UNDEFINED;
   utils.PostExperimentals = UNDEFINED;
   typed_array_setup = UNDEFINED;
 }
 
 
 function InitializeBuiltinTypedArrays(utils, rng_state, rempio2result) {
   var setup_list =  typed_array_setup;
 
   for ( ; !IS_UNDEFINED(setup_list); setup_list = setup_list.next) {
     setup_list(rng_state, rempio2result);
   }
 }
 
 
 // -----------------------------------------------------------------------
 
-%OptimizeObjectForAddingMultipleProperties(utils, 15);
+%OptimizeObjectForAddingMultipleProperties(utils, 14);
 
 utils.Import = Import;
 utils.ImportNow = ImportNow;
 utils.Export = Export;
 utils.ImportFromExperimental = ImportFromExperimental;
 utils.SetFunctionName = SetFunctionName;
 utils.InstallConstants = InstallConstants;
 utils.InstallFunctions = InstallFunctions;
 utils.InstallGetter = InstallGetter;
 utils.InstallGetterSetter = InstallGetterSetter;
@@ skipping 43 matching lines @@
 
 extrasUtils.uncurryThis = function uncurryThis(func) {
   return function(thisArg) {
     return %Apply(func, thisArg, arguments, 1, arguments.length - 1);
   };
 };
 
 %ToFastProperties(extrasUtils);
 
 })