Removes dartc reliance on its own libraries, now can be targeted at any implementation's libraries

compiler/java/com/google/dart/compiler/InternalCompilerException.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.compiler;
 
 /**
  * Exception thrown when the compiler encounters an unexpected internal error.
  */
 public class InternalCompilerException extends RuntimeException {
 
   public InternalCompilerException(String message) {
     super(message);
   }
+  
+  public InternalCompilerException(String message, Throwable t) {
+    super(message, t);
+  }
 }