[es6] Fix invalid ToString in implementation of ToName.

src/full-codegen/mips64/full-codegen-mips64.cc

Index: src/full-codegen/mips64/full-codegen-mips64.cc
diff --git a/src/full-codegen/mips64/full-codegen-mips64.cc b/src/full-codegen/mips64/full-codegen-mips64.cc
index 5ff766b4b4621579c33e40daddf4628a4dd5e1f3..d01b1506fe876da6e963241c0cddf986ec71140a 100644
--- a/src/full-codegen/mips64/full-codegen-mips64.cc
+++ b/src/full-codegen/mips64/full-codegen-mips64.cc
@@ -3822,9 +3822,8 @@ void FullCodeGenerator::EmitToName(CallRuntime* expr) {
   __ GetObjectType(v0, a1, a1);
   __ Branch(&done_convert, le, a1, Operand(LAST_NAME_TYPE));
   __ bind(&convert);
-  ToStringStub stub(isolate());
-  __ mov(a0, v0);
-  __ CallStub(&stub);
+  __ Push(v0);
+  __ CallRuntime(Runtime::kToName, 1);
   __ bind(&done_convert);
   context()->Plug(v0);
 }