Clean up after some recent code changes

pkg/analyzer_plugin/test/plugin/mocks.dart

Index: pkg/analyzer_plugin/test/plugin/mocks.dart
diff --git a/pkg/analyzer_plugin/test/plugin/mocks.dart b/pkg/analyzer_plugin/test/plugin/mocks.dart
index b8f784d772836a7cb4dd384c49db2d3f22fca699..a9ff4d8ad704e524929bd9a38dca84c1bd177659 100644
--- a/pkg/analyzer_plugin/test/plugin/mocks.dart
+++ b/pkg/analyzer_plugin/test/plugin/mocks.dart
@@ -119,14 +119,9 @@ class MockChannel implements PluginCommunicationChannel {
  * A concrete implementation of a server plugin that is suitable for testing.
  */
 class MockServerPlugin extends ServerPlugin {
-  MockChannel mockChannel = new MockChannel();
-
   MockServerPlugin(ResourceProvider resourceProvider) : super(resourceProvider);
 
   @override
-  PluginCommunicationChannel get channel => mockChannel;
-
-  @override
   List<String> get fileGlobsToAnalyze => <String>['*.dart'];
 
   @override