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 799f96d08816398815d276665f0ba3d1df5e72cc..f1244c51f36de92e0b89def1e3812871feb13162 100644
--- a/src/full-codegen.h
+++ b/src/full-codegen.h
@@ -527,11 +527,11 @@ 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_; }