[debugger] fix crash in debug-evaluate when retrieving values in TDZ.

test/mjsunit/regress/regress-crbug-605581.js

-// Copyright 2015 the V8 project authors. All rights reserved.
+// Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug --allow-natives-syntax
+// Flags: --expose-debug-as debug
 
 var Debug = debug.Debug;
-
 var exception = null;
 
 function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
-    var scope = exec_state.frame().scope(0);
-    assertEquals(5, scope.scopeObject().property("i").value().value());
+    assertThrows(() => exec_state.frame(0).evaluate("bar.baz"), ReferenceError);
   } catch (e) {
     exception = e;
   }
 }
 
-function f() {
-  eval('var i = 5');
-  debugger;
-}
-
-f();
-f();
-
-%OptimizeFunctionOnNextCall(f);
 Debug.setListener(listener);
 
-f();
+(function() {
+  debugger;    // bar is still in TDZ at this point.
+  let bar = 1;
+  (x => bar);  // force bar to be context-allocated.
+})();
 
+Debug.setListener(null);
 assertNull(exception);