Add CompilationUnit abstraction for tracking "project files".

dart/site/try/src/compilation.dart

 // Copyright (c) 2013, 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.
 
 library trydart.compilation;
 
 import 'dart:html' show
     Blob,
     Element,
     ErrorEvent,
     IFrameElement,
     MessageEvent,
     Url,
-    Worker;
+    Worker,
+    window;
 
 import 'dart:async' show
     Timer;
 
 import 'dart:isolate' show
     ReceivePort,
     SendPort;
 
 import 'editor.dart' show
     addDiagnostic,
-    currentSource,
     isMalformedInput;
 
 import 'run.dart' show
     makeOutputFrame;
 
 import 'ui.dart' show
     buildButton,
     outputDiv,
     outputFrame;
 
@@ skipping 20 matching lines @@
  * are encouraged to use a prefix based on their domain name, expressed
  * in reverse order.  For example, a URI scheme name of com-example-info
  * might be registered by the vendor that owns the example.com domain
  * name.
  */
 const String PRIVATE_SCHEME = 'org-trydart';
 
 SendPort compilerPort;
 Timer compilerTimer;
 
+// TODO(ahe): Remove this.
+String get currentSource => window.localStorage['currentSource'];
+
+void set currentSource(String text) {
+  window.localStorage['currentSource'] = text;
+}
+
 void scheduleCompilation() {
   if (compilationPaused) return;
   if (compilerTimer != null) {
     compilerTimer.cancel();
     compilerTimer = null;
   }
   compilerTimer =
       new Timer(const Duration(milliseconds: 500), startCompilation);
 }
 
@@ skipping 223 matching lines @@
       compile(list[0], list[1]);
     } catch (exception, stack) {
       port.send('$exception\n$stack');
     }
   });
   var notTrue = false; // Confuse the analyzer.
   if (notTrue) {
     cacheCompiler.compilerFor(null);
   }
 }