[Atomics] Remove Atomics code stubs; use TF ops

src/x64/interface-descriptors-x64.cc

Index: src/x64/interface-descriptors-x64.cc
diff --git a/src/x64/interface-descriptors-x64.cc b/src/x64/interface-descriptors-x64.cc
index 0b887a29af3fe9088b89dc0d2bf9b663b3d7ef63..1eb0055cf7542d1357d85209b210307012622004 100644
--- a/src/x64/interface-descriptors-x64.cc
+++ b/src/x64/interface-descriptors-x64.cc
@@ -420,15 +420,6 @@ void ResumeGeneratorDescriptor::InitializePlatformSpecific(
   data->InitializePlatformSpecific(arraysize(registers), registers);
 }
 
-void AtomicsLoadDescriptor::InitializePlatformSpecific(
-    CallInterfaceDescriptorData* data) {
-  Register registers[] = {
-      rdx,  // the typedarray object
-      rax   // the index to load (untagged)
-  };
-  data->InitializePlatformSpecific(arraysize(registers), registers);
-}
-
 }  // namespace internal
 }  // namespace v8