Revert of [Atomics] Remove Atomics code stubs; use TF ops

src/compiler/raw-machine-assembler.h

Index: src/compiler/raw-machine-assembler.h
diff --git a/src/compiler/raw-machine-assembler.h b/src/compiler/raw-machine-assembler.h
index 735fff40660854b11a9d47d7a81e2eb5faffa7b7..2d4d539ee07d31023cd18aba441fd318aa9562c8 100644
--- a/src/compiler/raw-machine-assembler.h
+++ b/src/compiler/raw-machine-assembler.h
@@ -131,11 +131,6 @@
               WriteBarrierKind write_barrier) {
     return AddNode(machine()->Store(StoreRepresentation(rep, write_barrier)),
                    base, index, value);
-  }
-
-  // Atomic memory operations.
-  Node* AtomicLoad(MachineType rep, Node* base, Node* index) {
-    return AddNode(machine()->AtomicLoad(rep), base, index);
   }
 
   // Arithmetic Operations.