[turbofan] Switch message object manipulation to JSOperator.

src/compiler/ast-graph-builder.h

Index: src/compiler/ast-graph-builder.h
diff --git a/src/compiler/ast-graph-builder.h b/src/compiler/ast-graph-builder.h
index 0139261081e7157b4aa51ea407fe7047b8e0a2a6..edcdb36487ac48107a0e7ca72c1e88ad06df7633 100644
--- a/src/compiler/ast-graph-builder.h
+++ b/src/compiler/ast-graph-builder.h
@@ -308,10 +308,6 @@ class AstGraphBuilder : public AstVisitor {
   Node* BuildLoadObjectField(Node* object, int offset);
   Node* BuildLoadImmutableObjectField(Node* object, int offset);
 
-  // Builders for accessing external references.
-  Node* BuildLoadExternal(ExternalReference ref, MachineType type);
-  Node* BuildStoreExternal(ExternalReference ref, MachineType type, Node* val);
-
   // Builders for automatic type conversion.
   Node* BuildToBoolean(Node* input);
   Node* BuildToName(Node* input, BailoutId bailout_id);