Fix DebugEvaluate for generators.

test/mjsunit/regress-3225.js

+// Copyright 2014 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  --harmony-generators
+
+Debug = debug.Debug
+
+var debug_step = 0;
+var failure = null;
+
+function listener(event, exec_state, event_data, data) {
+  if (event != Debug.DebugEvent.Break) return;
+  try {
+    if (debug_step == 0) {
+      assertEquals(1, exec_state.frame(0).evaluate('a').value());
+      assertEquals(3, exec_state.frame(0).evaluate('b').value());
+      exec_state.frame(0).evaluate("a = 4").value();
+      debug_step++;
+    } else {
+      assertEquals(4, exec_state.frame(0).evaluate('a').value());
+      assertEquals(3, exec_state.frame(0).evaluate('b').value());
+      exec_state.frame(0).evaluate("b = 5").value();
+    }
+  } catch (e) {
+    failure = e;
+  }
+}
+
+Debug.setListener(listener);
+
+function* generator(a, b) {
+  var b = 3;  // Shadows a parameter.
+  debugger;
+  yield a;
+  yield b;
+  debugger;
+  return b;
+}
+
+var foo = generator(1, 2);
+
+assertEquals(4, foo.next().value);
+assertEquals(3, foo.next().value);
+assertEquals(5, foo.next().value);
+assertNull(failure);
+
+Debug.setListener(null);