Replace boolean indications of strict mode by an enum value.

src/scopes.h

Index: src/scopes.h
diff --git a/src/scopes.h b/src/scopes.h
index 72f1e31878efb744ac8d1210f531d1d16b7a0026..40898f8c6b36bad9e83f15ca66303848d037db95 100644
--- a/src/scopes.h
+++ b/src/scopes.h
@@ -201,9 +201,9 @@ class Scope: public ZoneObject {
   // Inform the scope that the corresponding code contains an eval call.
   void RecordEvalCall() { if (!is_global_scope()) scope_calls_eval_ = true; }
 
-  // Enable strict mode for the scope (unless disabled by a global flag).
-  void EnableStrictMode() {
-    strict_mode_ = FLAG_strict_mode;
+  // 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;
   }
 
   // ---------------------------------------------------------------------------
@@ -219,7 +219,7 @@ 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_; }
+  bool is_strict_mode() const { return strict_mode_flag() == kStrictMode; }
   bool is_strict_mode_eval_scope() const {
     return is_eval_scope() && is_strict_mode();
   }
@@ -244,6 +244,8 @@ class Scope: public ZoneObject {
   // ---------------------------------------------------------------------------
   // Accessors.
 
+  StrictModeFlag strict_mode_flag() const { return strict_mode_flag_; }
+
   // The variable corresponding the 'this' value.
   Variable* receiver() { return receiver_; }
 
@@ -386,7 +388,7 @@ 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.
-  bool strict_mode_;
+  StrictModeFlag strict_mode_flag_;
 
   // Computed via PropagateScopeInfo.
   bool outer_scope_calls_non_strict_eval_;