Update unit tests

dart/tests/try/poi/library_updater_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 of LibraryUpdater (one compilation unit per library).
 library trydart.library_updater_test;
 
-import 'dart:convert' show
-    UTF8;
-
 import 'package:dart2js_incremental/library_updater.dart' show
     IncrementalCompilerContext,
     LibraryUpdater,
     Update;
 
+import 'package:compiler/src/dart2jslib.dart' show
+    Script;
+
+import 'package:compiler/src/source_file.dart' show
+    StringSourceFile;
+
 import 'compiler_test_case.dart';
 
 void nolog(_) {}
 
+Script newScriptFrom(LibraryElement library, String newSource) {
+  Script script = library.entryCompilationUnit.script;
+  return script.copyWithFile(
+      new StringSourceFile(script.file.filename, newSource));
+}
+
 class LibraryUpdaterTestCase extends CompilerTestCase {
   final String newSource;
 
   final bool expectedCanReuse;
 
   final List<String> expectedUpdates;
 
   LibraryUpdaterTestCase(
       {String before,
        String after,
        bool canReuse,
        List<String> updates})
       : this.newSource = after,
         this.expectedCanReuse = canReuse,
         this.expectedUpdates = updates,
         super(before);
 
   Future run() => loadMainApp().then((LibraryElement library) {
     var context = new IncrementalCompilerContext();
     LibraryUpdater updater =
         new LibraryUpdater(this.compiler, null, nolog, nolog, context);
     context.registerUriWithUpdates([scriptUri]);
     bool actualCanReuse =
-        updater.canReuseLibrary(library, UTF8.encode(newSource));
+        updater.canReuseLibrary(
+            library, <Script>[newScriptFrom(library, newSource)]);
     Expect.equals(expectedCanReuse, actualCanReuse);
 
     Expect.setEquals(
         expectedUpdates.toSet(),
         updater.updates.map(nameOfUpdate).toSet());
   });
 
   String toString() => 'Before:\n$source\n\n\nAfter:\n$newSource';
 }
 
@@ skipping 67 matching lines @@
           new LibraryUpdaterTestCase(
               before: 'main() => null;',
               after: 'main() {}',
               canReuse: true,
               updates: ['main']),
 
           // TODO(ahe): When supporting class members, test abstract methods.
       ]
   );
 }