Debugger: use FrameInspector in ScopeIterator to find context.

test/mjsunit/regress/regress-4309-2.js

+// Copyright 2015 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
+
+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());
+  } catch (e) {
+    exception = e;
+  }
+}
+
+function f() {
+  eval('var i = 5');
+  debugger;
+}
+
+f();
+f();
+
+%OptimizeFunctionOnNextCall(f);
+Debug.setListener(listener);
+
+f();
+
+assertNull(exception);