Update the analysis server diagnostic page - re-enable code completion and overlay pages,

pkg/analysis_server/lib/src/server/http_server.dart

Index: pkg/analysis_server/lib/src/server/http_server.dart
diff --git a/pkg/analysis_server/lib/src/server/http_server.dart b/pkg/analysis_server/lib/src/server/http_server.dart
index a8288fce7b55323531859e8d8b2d1fbf1f7fb03c..53a12e49c0e6f73f24675a8a8a486d363213101e 100644
--- a/pkg/analysis_server/lib/src/server/http_server.dart
+++ b/pkg/analysis_server/lib/src/server/http_server.dart
@@ -7,8 +7,8 @@ import 'dart:io';
 
 import 'package:analysis_server/src/channel/web_socket_channel.dart';
 import 'package:analysis_server/src/socket_server.dart';
+import 'package:analysis_server/src/status/diagnostics.dart';
 import 'package:analysis_server/src/status/get_handler.dart';
-import 'package:analysis_server/src/status/get_handler2.dart';
 
 /**
  * Instances of the class [HttpServer] implement a simple HTTP server. The
@@ -96,8 +96,10 @@ class HttpAnalysisServer {
   void _handleGetRequest(HttpRequest request) {
     if (getHandler == null) {
       if (socketServer.analysisServer.options.enableNewAnalysisDriver) {
-        getHandler = new GetHandler2(socketServer, _printBuffer);
+        // TODO(devoncarew): Remove GetHandler2.
+        getHandler = new DiagnosticsSite(socketServer, _printBuffer);
       } else {
+        // TODO(devoncarew): GetHandler is essentially dead code.
         getHandler = new GetHandler(socketServer, _printBuffer);
       }
     }
@@ -146,3 +148,13 @@ class HttpAnalysisServer {
     response.close();
   }
 }
+
+/**
+ * Instances of the class [AbstractGetHandler] handle GET requests.
+ */
+abstract class AbstractGetHandler {
+  /**
+   * Handle a GET request received by the HTTP server.
+   */
+  void handleGetRequest(HttpRequest request);
+}