Fix source_update_test on Chrome.

dart/site/try/src/interaction_manager.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.
 
 library trydart.interaction_manager;
 
 import 'dart:html';
 
 import 'dart:convert' show
     JSON;
@@ skipping 48 matching lines @@
     isCollapsed;
 
 import 'editor.dart' as editor;
 
 import 'mock.dart' as mock;
 
 import 'settings.dart' as settings;
 
 import 'shadow_root.dart' show
     getShadowRoot,
+    getText,
     removeShadowRootPolyfill,
     setShadowRoot;
 
 const String TRY_DART_NEW_DEFECT =
     'https://code.google.com/p/dart/issues/entry'
     '?template=Try+Dart+Internal+Error';
 
 /**
  * UI interaction manager for the entire application.
  */
@@ skipping 230 matching lines @@
           state = tokenizeAndHighlight(
               line, state, offset, trySelection, lineNodes);
           offset += line.length;
           nodes.add(makeLine(lineNodes, state));
         }
 
         node.parent.insertAllBefore(nodes, node);
         node.remove();
         trySelection.adjust(selection);
 
+        // TODO(ahe): We know almost exactly what has changed.  It could be
+        // more efficient to only communicate what changed.
+        context.currentCompilationUnit.content = getText(mainEditorPane);
+
         // Discard highlighting mutations.
         observer.takeRecords();
         return;
       }
     }
 
+    // TODO(ahe): Use getText(mainEditorPane) instead.
     removeShadowRootPolyfill(mainEditorPane);
 
     String currentText = mainEditorPane.text;
     trySelection.updateText(currentText);
 
     context.currentCompilationUnit.content = currentText;
 
     editor.seenIdentifiers = new Set<String>.from(mock.identifiers);
 
     editor.isMalformedInput = false;
@@ skipping 556 matching lines @@
   return text.split(new RegExp('^', multiLine: true));
 }
 
 void removeCodeCompletion() {
   List<Node> highlighting =
       mainEditorPane.querySelectorAll('.dart-code-completion');
   for (Element element in highlighting) {
     element.remove();
   }
 }