Introduced Atomic8 and added no-barrier Atomic8 accessors.

src/atomicops_internals_arm_gcc.h

Index: src/atomicops_internals_arm_gcc.h
diff --git a/src/atomicops_internals_arm_gcc.h b/src/atomicops_internals_arm_gcc.h
index 918920d02ae66e5723c0bb9993473be49f66036b..258a668da353753db9ce453fb677124a608b762f 100644
--- a/src/atomicops_internals_arm_gcc.h
+++ b/src/atomicops_internals_arm_gcc.h
@@ -311,6 +311,14 @@ inline Atomic32 Release_Load(volatile const Atomic32* ptr) {
   return *ptr;
 }
 
+// Byte accessors.
+
+inline void NoBarrier_Store(volatile Atomic8* ptr, Atomic8 value) {
+  *ptr = value;
+}
+
+inline Atomic8 NoBarrier_Load(volatile const Atomic8* ptr) { return *ptr; }
+
 } }  // namespace v8::internal
 
 #endif  // V8_ATOMICOPS_INTERNALS_ARM_GCC_H_