[debugger] add test case for throwing in generators.

R=neis@chromium.org

Review-Url: https://codereview.chromium.org/2117303003
Cr-Commit-Position: refs/heads/master@{#37520}

test/mjsunit/es6/debug-exception-generators.js

+// 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
+
+Debug = debug.Debug
+
+var exception = null;
+var log = [];
+
+function listener(event, exec_state, event_data, data) {
+  if (event != Debug.DebugEvent.Exception) return;
+  try {
+    var line = exec_state.frame(0).sourceLineText();
+    var match = /Exception (\w)/.exec(line);
+    assertNotNull(match);
+    assertEquals(match[1], event_data.exception());
+    log.push(match[1]);
+  } catch (e) {
+    exception = e;
+  }
+}
+
+
+function* g() {
+  try {
+    throw "a";  // Ordinary throw. Exception a
+  } catch (e) {}
+  try {
+    yield 1;  // Caught internally. Exception b
+  } catch (e) {}
+  yield 2;
+  yield 3;    // Caught externally. Exception c
+  yield 4;
+}
+
+Debug.setListener(listener);
+Debug.setBreakOnException();
+var g_obj = g();
+assertEquals(1, g_obj.next().value);
+assertEquals(2, g_obj.throw("b").value);
+assertEquals(3, g_obj.next().value);
+assertThrows(() => g_obj.throw("c"));
+assertThrows(() => g_obj.throw("d"));  // Closed generator. Exception d
+Debug.setListener(null);
+Debug.clearBreakOnException();
+assertEquals(["a", "b", "c", "d"], log);
+assertNull(exception);