Strict mode arguments do not share binding with formal parameters.

src/scopes.h

Index: src/scopes.h
diff --git a/src/scopes.h b/src/scopes.h
index a9220eb827566e94e7a126f1085bdc90d6c3a67c..123c4d867f251d1c77e264eb79b34b9817b2afcd 100644
--- a/src/scopes.h
+++ b/src/scopes.h
@@ -193,6 +193,10 @@ class Scope: public ZoneObject {
   // Inform the scope that the corresponding code contains an eval call.
   void RecordEvalCall() { scope_calls_eval_ = true; }
 
+  // Enable strict mode for the scope (unless disabled by a global flag).
+  void EnableStrictMode() {
+    strict_mode_ = FLAG_strict_mode;
+  }
 
   // ---------------------------------------------------------------------------
   // Predicates.
@@ -201,6 +205,7 @@ class Scope: public ZoneObject {
   bool is_eval_scope() const { return type_ == EVAL_SCOPE; }
   bool is_function_scope() const { return type_ == FUNCTION_SCOPE; }
   bool is_global_scope() const { return type_ == GLOBAL_SCOPE; }
+  bool is_strict_mode() const { return strict_mode_; }
 
   // Information about which scopes calls eval.
   bool calls_eval() const { return scope_calls_eval_; }
@@ -363,6 +368,7 @@ class Scope: public ZoneObject {
   bool scope_inside_with_;  // this scope is inside a 'with' of some outer scope
   bool scope_contains_with_;  // this scope contains a 'with' statement
   bool scope_calls_eval_;  // this scope contains an 'eval' call
+  bool strict_mode_;  // this scope is a strict mode scope
 
   // Computed via PropagateScopeInfo.
   bool outer_scope_calls_eval_;
@@ -428,6 +434,8 @@ class Scope: public ZoneObject {
     scope_inside_with_ = false;
     scope_contains_with_ = false;
     scope_calls_eval_ = false;
+    // Inherit the strict mode from the parent scope.
+    strict_mode_ = (outer_scope != NULL) && outer_scope->strict_mode_;
     outer_scope_calls_eval_ = false;
     inner_scope_calls_eval_ = false;
     outer_scope_is_eval_scope_ = false;