[Atomics] Remove Atomics code stubs; use TF ops

src/compiler/code-stub-assembler.h

Index: src/compiler/code-stub-assembler.h
diff --git a/src/compiler/code-stub-assembler.h b/src/compiler/code-stub-assembler.h
index b73c723eaa4fcd4fd01d21611443d0edd1dc7469..883ec669d176ea865a1d57e2c8063bef045b5c67 100644
--- a/src/compiler/code-stub-assembler.h
+++ b/src/compiler/code-stub-assembler.h
@@ -195,6 +195,7 @@ class CodeStubAssembler {
   // Load raw memory location.
   Node* Load(MachineType rep, Node* base);
   Node* Load(MachineType rep, Node* base, Node* index);
+  Node* AtomicLoad(MachineType rep, Node* base, Node* index);
 
   // Store value to raw memory location.
   Node* Store(MachineRepresentation rep, Node* base, Node* value);
@@ -395,6 +396,8 @@ class CodeStubAssembler {
   Node* TruncateTaggedToWord32(Node* context, Node* value);
   // Truncate to int32 using JavaScript truncation mode.
   Node* TruncateFloat64ToInt32(Node* value);
+  // No-op on 32-bit, otherwise zero extend.
+  Node* ChangeUint32ToWord(Node* value);
 
   // Type conversions.
   // Throws a TypeError for {method_name} if {value} is not coercible to Object,