Implement strict mode arguments caller/callee.

src/codegen-inl.h

Index: src/codegen-inl.h
diff --git a/src/codegen-inl.h b/src/codegen-inl.h
index 54677894cd208d0ca342eb50c66d550811805305..f7da54a2402749917a6b10cb27e8595f54f6bd4b 100644
--- a/src/codegen-inl.h
+++ b/src/codegen-inl.h
@@ -55,8 +55,12 @@ bool CodeGenerator::is_eval() { return info_->is_eval(); }
 
 Scope* CodeGenerator::scope() { return info_->function()->scope(); }
 
+bool CodeGenerator::is_strict_mode() {
+  return info_->function()->strict_mode();
+}
+
 StrictModeFlag CodeGenerator::strict_mode_flag() {
-  return info_->function()->strict_mode() ? kStrictMode : kNonStrictMode;
+  return is_strict_mode() ? kStrictMode : kNonStrictMode;
 }
 
 } }  // namespace v8::internal