Introduce extended mode.

src/scopes.h

Index: src/scopes.h
diff --git a/src/scopes.h b/src/scopes.h
index d08e2948242d1e52e61c33853d5e8281a2063b27..3a8a59384cace8ded44eabcac21de789a59c1592 100644
--- a/src/scopes.h
+++ b/src/scopes.h
@@ -192,8 +192,8 @@ class Scope: public ZoneObject {
   void RecordEvalCall() { if (!is_global_scope()) scope_calls_eval_ = true; }
 
   // Set the strict mode flag (unless disabled by a global flag).
-  void SetStrictModeFlag(StrictModeFlag strict_mode_flag) {
-    strict_mode_flag_ = FLAG_strict_mode ? strict_mode_flag : kNonStrictMode;
+  void SetLanguageMode(LanguageMode language_mode) {
+    language_mode_ = language_mode;
   }
 
   // Position in the source where this scope begins and ends.
@@ -240,15 +240,20 @@ class Scope: public ZoneObject {
   bool is_declaration_scope() const {
     return is_eval_scope() || is_function_scope() || is_global_scope();
   }
-  bool is_strict_mode() const { return strict_mode_flag() == kStrictMode; }
-  bool is_strict_mode_eval_scope() const {
-    return is_eval_scope() && is_strict_mode();
+  bool is_classic_mode() const {
+    return language_mode() == CLASSIC_MODE;
+  }
+  bool is_extended_mode() const {
+    return language_mode() == EXTENDED_MODE;
+  }
+  bool is_strict_or_extended_eval_scope() const {
+    return is_eval_scope() && !is_classic_mode();
   }
 
   // Information about which scopes calls eval.
   bool calls_eval() const { return scope_calls_eval_; }
   bool calls_non_strict_eval() {
-    return scope_calls_eval_ && !is_strict_mode();
+    return scope_calls_eval_ && is_classic_mode();
   }
   bool outer_scope_calls_non_strict_eval() const {
     return outer_scope_calls_non_strict_eval_;
@@ -268,8 +273,8 @@ class Scope: public ZoneObject {
   // The type of this scope.
   ScopeType type() const { return type_; }
 
-  // The strict mode of this scope.
-  StrictModeFlag strict_mode_flag() const { return strict_mode_flag_; }
+  // The language mode of this scope.
+  LanguageMode language_mode() const { return language_mode_; }
 
   // The variable corresponding the 'this' value.
   Variable* receiver() { return receiver_; }
@@ -425,7 +430,7 @@ class Scope: public ZoneObject {
   // the 'eval' call site this scope is the declaration scope.
   bool scope_calls_eval_;
   // This scope is a strict mode scope.
-  StrictModeFlag strict_mode_flag_;
+  LanguageMode language_mode_;
   // Source positions.
   int start_position_;
   int end_position_;