[debugger] fix debug-evaluate wrt shadowed context var.

test/mjsunit/debug-evaluate-closure.js

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 18 matching lines @@
 
 Debug = debug.Debug;
 var listened = false;
 
 function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
     assertEquals("goo", exec_state.frame(0).evaluate("goo").value());
     exec_state.frame(0).evaluate("goo = 'goo foo'");
     assertEquals("bar return", exec_state.frame(0).evaluate("bar()").value());
-    assertEquals("inner bar", exec_state.frame(0).evaluate("inner").value());
-    assertEquals("outer bar", exec_state.frame(0).evaluate("outer").value());
+    // Check that calling bar() has no effect to context-allocated variables.
+    // TODO(yangguo): reevaluate this if we no longer update context from copy.
+    assertEquals("inner", exec_state.frame(0).evaluate("inner").value());
+    assertEquals("outer", exec_state.frame(0).evaluate("outer").value());
+
     assertEquals("baz inner", exec_state.frame(0).evaluate("baz").value());
     assertEquals("baz outer", exec_state.frame(1).evaluate("baz").value());
     exec_state.frame(0).evaluate("w = 'w foo'");
     exec_state.frame(0).evaluate("inner = 'inner foo'");
     exec_state.frame(0).evaluate("outer = 'outer foo'");
     exec_state.frame(0).evaluate("baz = 'baz inner foo'");
     exec_state.frame(1).evaluate("baz = 'baz outer foo'");
     listened = true;
   } catch (e) {
     print(e);
     print(e.stack);
   }
 }
 
 Debug.setListener(listener);
 
 var outer = "outer";
 var baz = "baz outer";
 
 function foo() {
   var inner = "inner";
   var baz = "baz inner";
   var goo = "goo";
   var withw = { w: "w" };
   var withv = { v: "v" };
 
   with (withv) {
     var bar = function bar() {
       assertEquals("goo foo", goo);
-      inner = "inner bar";
-      outer = "outer bar";
+      inner = "inner bar";  // this has no effect, when called from debug-eval
+      outer = "outer bar";  // this has no effect, when called from debug-eval
       v = "v bar";
       return "bar return";
     };
   }
 
   with (withw) {
     debugger;
   }
 
   assertEquals("inner foo", inner);
   assertEquals("baz inner foo", baz);
   assertEquals("w foo", withw.w);
   assertEquals("v bar", withv.v);
 }
 
 foo();
 assertEquals("outer foo", outer);
 assertEquals("baz outer foo", baz);
 assertTrue(listened);
 Debug.setListener(null);