[Math] implement Math.random as TFJ builtin.

src/snapshot/partial-serializer.cc

 // Copyright 2016 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.
 
 #include "src/snapshot/partial-serializer.h"
 #include "src/snapshot/startup-serializer.h"
 
 #include "src/objects-inl.h"
 
 namespace v8 {
@@ skipping 15 matching lines @@
     reference_map()->AddAttachedReference(context->global_proxy());
     // The bootstrap snapshot has a code-stub context. When serializing the
     // partial snapshot, it is chained into the weak context list on the isolate
     // and it's next context pointer may point to the code-stub context.  Clear
     // it before serializing, it will get re-added to the context list
     // explicitly when it's loaded.
     if (context->IsNativeContext()) {
       context->set(Context::NEXT_CONTEXT_LINK,
                    isolate_->heap()->undefined_value());
       DCHECK(!context->global_object()->IsUndefined(context->GetIsolate()));
+      // Reset math random cache to get fresh random numbers.
+      context->set_math_random_index(Smi::kZero);
+      context->set_math_random_cache(isolate_->heap()->undefined_value());
     }
   }
   VisitPointer(o);
   SerializeDeferredObjects();
   Pad();
 }
 
 void PartialSerializer::SerializeObject(HeapObject* obj, HowToCode how_to_code,
                                         WhereToPoint where_to_point, int skip) {
   if (obj->IsMap()) {
@@ skipping 59 matching lines @@
   // would cause dupes.
   DCHECK(!o->IsScript());
   return o->IsName() || o->IsSharedFunctionInfo() || o->IsHeapNumber() ||
          o->IsCode() || o->IsScopeInfo() || o->IsAccessorInfo() ||
          o->map() ==
              startup_serializer_->isolate()->heap()->fixed_cow_array_map();
 }
 
 }  // namespace internal
 }  // namespace v8