Introduce extended mode.

src/full-codegen.h

Index: src/full-codegen.h
diff --git a/src/full-codegen.h b/src/full-codegen.h
index 59bdf4525d96e1c5c22ee8c73fc78bb30c3a82e9..e8915fc8c2aca3ccc8cd4c391f3876869ac35191 100644
--- a/src/full-codegen.h
+++ b/src/full-codegen.h
@@ -529,11 +529,11 @@ class FullCodeGenerator: public AstVisitor {
   Handle<Script> script() { return info_->script(); }
   bool is_eval() { return info_->is_eval(); }
   bool is_native() { return info_->is_native(); }
-  bool is_strict_mode() {
-    return strict_mode_flag() == kStrictMode;
+  bool is_classic_mode() {
+    return language_mode() == CLASSIC_MODE;
   }
-  StrictModeFlag strict_mode_flag() {
-    return function()->strict_mode_flag();
+  LanguageMode language_mode() {
+    return function()->language_mode();
   }
   FunctionLiteral* function() { return info_->function(); }
   Scope* scope() { return scope_; }