[base] Drop obsolete Thread::YieldCPU.

src/base/platform/platform-win32.cc

 // Copyright 2012 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.
 
 // Platform-specific code for Win32.
 
 // Secure API functions are not available using MinGW with msvcrt.dll
 // on Windows XP. Make sure MINGW_HAS_SECURE_API is not defined to
 // disable definition of secure API functions in standard headers that
 // would conflict with our own implementation.
@@ skipping 1366 matching lines @@
   return TlsGetValue(static_cast<DWORD>(key));
 }
 
 
 void Thread::SetThreadLocal(LocalStorageKey key, void* value) {
   BOOL result = TlsSetValue(static_cast<DWORD>(key), value);
   USE(result);
   DCHECK(result);
 }
 
-
-
-void Thread::YieldCPU() {
-  Sleep(0);
-}
-
-} }  // namespace v8::base
+}  // namespace base
+}  // namespace v8