Move Compiler.libraries to LibraryLoader.

tests/compiler/dart2js/in_user_code_test.dart

 // Copyright (c) 2014, 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.
 
 // Test that the helper [Compiler.inUserCode] works as intended.
 
 import 'package:async_helper/async_helper.dart';
 import 'package:expect/expect.dart';
 
 import 'memory_compiler.dart';
@@ skipping 36 matching lines @@
                              options: ['--analyze-only', '--analyze-all'],
                              packageRoot: Uri.parse('memory:pkg/'));
   Uri mainUri = null;
   if (entryPoints.length == 1) {
     mainUri = entryPoints[0];
   } else {
     compiler.librariesToAnalyzeWhenRun = entryPoints;
   }
   asyncTest(() => compiler.run(mainUri).then((_) {
     expectedResults.forEach((String uri, bool expectedResult) {
-      var element = compiler.libraries[uri];
+      var element = compiler.libraryLoader.lookupLibrary(Uri.parse(uri));
       Expect.isNotNull(element, "Unknown library '$uri'.");
       Expect.equals(expectedResult, compiler.inUserCode(element),
           expectedResult ? "Library '$uri' expected to be in user code"
                          : "Library '$uri' not expected to be in user code");
     });
   }));
 }
 
 void main() {
   test([Uri.parse('memory:main.dart')],
@@ skipping 20 matching lines @@
         'package:sup/boz.dart': true,
         'dart:core': false});
   test([Uri.parse('dart:async'), Uri.parse('package:sub/bar.dart')],
        {'package:sub/bar.dart': true,
         'package:sub/baz.dart': true,
         'package:sup/boz.dart': false,
         'dart:core': true,
         'dart:async': true});
 }