Optimize the typeof operator.

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index 7f0f66d0e5f7d2686ec10f4c1aeb6ca5684faef8..cdd57074ce2b0bd2280dc21a32c4e53d5e1a5523 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -4746,10 +4746,13 @@ void FullCodeGenerator::VisitUnaryOperation(UnaryOperation* expr) {
 
     case Token::TYPEOF: {
       Comment cmnt(masm_, "[ UnaryOperation (TYPEOF)");
-      { StackValueContext context(this);
+      {
+        AccumulatorValueContext context(this);
         VisitForTypeofValue(expr->expression());
       }
-      __ CallRuntime(Runtime::kTypeof, 1);
+      __ movp(rbx, rax);
+      TypeofStub typeof_stub(isolate());
+      __ CallStub(&typeof_stub);
       context()->Plug(rax);
       break;
     }