Guard local time posix functions from NaN value of invalid dates.

src/platform-win32.cc

 // Copyright 2006-2008 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
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 }
 
 // Returns the tickcounter based on timeGetTime.
 int64_t OS::Ticks() {
   return timeGetTime() * 1000;  // Convert to microseconds.
 }
 
 
 // Returns a string identifying the current timezone taking into
 // account daylight saving.
-char* OS::LocalTimezone(double time) {
+const char* OS::LocalTimezone(double time) {
   return Time(time).LocalTimezone();
 }
 
 
 // Returns the local time offset in milliseconds east of UTC without
 // taking daylight savings time into account.
 double OS::LocalTimeOffset() {
   // Use current time, rounded to the millisecond.
   Time t(TimeCurrentMillis());
   // Time::LocalOffset inlcudes any daylight savings offset, so subtract it.
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   // Release the thread handles
   CloseHandle(data_->sampler_thread_);
   CloseHandle(data_->profiled_thread_);
 }
 
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal