Add noBarrierStore to WTF and use it for spinlocks

third_party/WebKit/Source/wtf/Atomics.h

Index: third_party/WebKit/Source/wtf/Atomics.h
diff --git a/third_party/WebKit/Source/wtf/Atomics.h b/third_party/WebKit/Source/wtf/Atomics.h
index cdd631efe8aea48f021681350150f48f18274f7e..09b707e6f754336ddb7ab5cf99498b0c11417f3a 100644
--- a/third_party/WebKit/Source/wtf/Atomics.h
+++ b/third_party/WebKit/Source/wtf/Atomics.h
@@ -319,6 +319,17 @@ ALWAYS_INLINE float noBarrierLoad(volatile const float* ptr)
     return value;
 }
 
+ALWAYS_INLINE void noBarrierStore(volatile int* ptr, int value)
+{
+    *ptr = value;
+}
+
+ALWAYS_INLINE int noBarrierLoad(volatile const int* ptr)
+{
+    int value = *ptr;
+    return value;
+}
+
 #if defined(ADDRESS_SANITIZER)
 
 NO_SANITIZE_ADDRESS ALWAYS_INLINE void asanUnsafeReleaseStore(volatile unsigned* ptr, unsigned value)