[Atomics] code stubs for atomic operations

src/builtins.h

Index: src/builtins.h
diff --git a/src/builtins.h b/src/builtins.h
index e56369223c0ab1c0e14019a994032bfbae87b1ed..ce7585f583ee5975133989f89aa0914281c31aac 100644
--- a/src/builtins.h
+++ b/src/builtins.h
@@ -281,6 +281,7 @@ inline bool operator&(BuiltinExtraArguments lhs, BuiltinExtraArguments rhs) {
   V(MarkCodeAsToBeExecutedOnce, BUILTIN, UNINITIALIZED, kNoExtraICState)       \
   V(MarkCodeAsExecutedOnce, BUILTIN, UNINITIALIZED, kNoExtraICState)           \
   V(MarkCodeAsExecutedTwice, BUILTIN, UNINITIALIZED, kNoExtraICState)          \
+  V(AtomicsLoadCheck, BUILTIN, UNINITIALIZED, kNoExtraICState)                 \
   CODE_AGE_LIST_WITH_ARG(DECLARE_CODE_AGE_BUILTIN, V)
 
 // Define list of builtin handlers implemented in assembly.
@@ -593,6 +594,8 @@ class Builtins {
   static void Generate_MarkCodeAsExecutedOnce(MacroAssembler* masm);
   static void Generate_MarkCodeAsExecutedTwice(MacroAssembler* masm);
 
+  static void Generate_AtomicsLoadCheck(MacroAssembler* masm);
+
   static void InitBuiltinFunctionTable();
 
   bool initialized_;