Add strict mode, sloppy mode and strong mode UseCounters

src/parser.h

Index: src/parser.h
diff --git a/src/parser.h b/src/parser.h
index 62ff59bfeee124080b7ebd6321fbc838f5caee2b..36f419b6e0b13ccffcabd1c9e01acb59d9decf18 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -1200,6 +1200,9 @@ class Parser : public ParserBase<ParserTraits> {
   Expression* SpreadCallNew(Expression* function,
                             ZoneList<v8::internal::Expression*>* args, int pos);
 
+  void SetLanguageMode(Scope* scope, LanguageMode mode);
+  void RaiseLanguageMode(LanguageMode mode);
+
   Scanner scanner_;
   PreParser* reusable_preparser_;
   Scope* original_scope_;  // for ES5 function declarations in sloppy eval