Move frog/leg to lib/compiler/implementation.

frog/leg/script.dart

Index: frog/leg/script.dart
===================================================================
--- frog/leg/script.dart	(revision 5925)
+++ frog/leg/script.dart	(working copy)
@@ -1,12 +0,0 @@
-// 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.
-
-class Script {
-  final /* frog.SourceFile */ file;
-  final Uri uri;
-  Script(this.uri, this.file);
-
-  String get text() => (file === null) ? null : file.text;
-  String get name() => (file === null) ? null : file.filename;
-}