Fix a race in initialization of timezone cache in platform-win32.

src/runtime.cc

 // Copyright 2012 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 9565 matching lines @@
     return isolate->heap()->null_value();
   }
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_DateLocalTimezone) {
   SealHandleScope shs(isolate);
   ASSERT(args.length() == 1);
 
   CONVERT_DOUBLE_ARG_CHECKED(x, 0);
-  int64_t time = isolate->date_cache()->EquivalentTime(static_cast<int64_t>(x));
-  const char* zone = OS::LocalTimezone(static_cast<double>(time));
+  const char* zone =
+      isolate->date_cache()->LocalTimezone(static_cast<int64_t>(x));
   return isolate->heap()->AllocateStringFromUtf8(CStrVector(zone));
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_DateToUTC) {
   SealHandleScope shs(isolate);
   ASSERT(args.length() == 1);
 
   CONVERT_DOUBLE_ARG_CHECKED(x, 0);
   int64_t time = isolate->date_cache()->ToUTC(static_cast<int64_t>(x));
@@ skipping 5376 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal