Untangle RNG from v8 core

src/isolate-inl.h

 // Copyright 2011 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.
 
 #ifndef V8_ISOLATE_INL_H_
 #define V8_ISOLATE_INL_H_
 
 #include "src/debug.h"
 #include "src/isolate.h"
 #include "src/utils/random-number-generator.h"
@@ skipping 14 matching lines @@
 }
 
 
 bool Isolate::DebuggerHasBreakPoints() {
   return debug()->has_break_points();
 }
 
 
 RandomNumberGenerator* Isolate::random_number_generator() {
   if (random_number_generator_ == NULL) {
-    random_number_generator_ = new RandomNumberGenerator;
+    if (FLAG_random_seed != 0) {
+      random_number_generator_ = new RandomNumberGenerator(FLAG_random_seed);
+    } else {
+      random_number_generator_ = new RandomNumberGenerator();
+    }
   }
   return random_number_generator_;
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_ISOLATE_INL_H_