Removes dependency on v8 from dartc testing

compiler/java/com/google/dart/runner/RunnerError.java

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-package com.google.dart.runner;
-
-public class RunnerError extends Exception {
-  public RunnerError(String message) {
-    super(message);
-  }
-
-  RunnerError(String message, Throwable cause) {
-    super(message, cause);
-  }
-
-  RunnerError(Throwable cause) {
-    super(cause);
-  }
-}