Separate the API's used by ContextManager.

pkg/analysis_server/test/domain_execution_test.dart

Index: pkg/analysis_server/test/domain_execution_test.dart
diff --git a/pkg/analysis_server/test/domain_execution_test.dart b/pkg/analysis_server/test/domain_execution_test.dart
index 8fa92346ba5e7f49e2b2c3015bf0de97a3b2b4ab..2ff54e1aaf7e935a1db0bf6187a5927732b44151 100644
--- a/pkg/analysis_server/test/domain_execution_test.dart
+++ b/pkg/analysis_server/test/domain_execution_test.dart
@@ -8,6 +8,7 @@ import 'dart:async';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/constants.dart';
+import 'package:analysis_server/src/context_manager.dart';
 import 'package:analysis_server/src/domain_execution.dart';
 import 'package:analysis_server/src/plugin/server_plugin.dart';
 import 'package:analysis_server/src/protocol.dart';
@@ -225,7 +226,7 @@ main() {
       when(context.getLibrariesReferencedFromHtml(anyObject))
           .thenReturn([source6, source7]);
 
-      ServerContextManager manager = new ServerContextManagerMock();
+      ContextManager manager = new ServerContextManagerMock();
       when(manager.isInAnalysisRoot(anyString)).thenReturn(true);
 
       AnalysisServer server = new AnalysisServerMock();