[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 2d4d539ee07d31023cd18aba441fd318aa9562c8..735fff40660854b11a9d47d7a81e2eb5faffa7b7 100644
--- a/src/compiler/raw-machine-assembler.h
+++ b/src/compiler/raw-machine-assembler.h
@@ -133,6 +133,11 @@ class RawMachineAssembler {
                    base, index, value);
   }
 
+  // Atomic memory operations.
+  Node* AtomicLoad(MachineType rep, Node* base, Node* index) {
+    return AddNode(machine()->AtomicLoad(rep), base, index);
+  }
+
   // Arithmetic Operations.
   Node* WordAnd(Node* a, Node* b) {
     return AddNode(machine()->WordAnd(), a, b);