fixes #6, refactor to use AnalysisError/Listener throughout dev_compiler

test/codegen/temps.dart

 // Copyright (c) 2015, 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.
 
 class FormalCollision {
   // These shouldn't collide (see issue #136)
   int _x, __x;
   // This shouldn't generate a keyword as an identifier.
   Function _function;
   FormalCollision(this._x, this.__x, this._function);
 }
 
 class OptionalArg {
-  int _opt;
+  int opt, _opt;
   OptionalArg([this._opt = 123]);
-  OptionalArg.named({this._opt: 456});
+  OptionalArg.named({this.opt: 456});
 }
 
 main() {
   print(new FormalCollision(1, 2, (x) => x));
   print(new OptionalArg()._opt);
   print(new OptionalArg.named()._opt);
 }