Remove references to AnalysisDriver from the plugin mixin classes

pkg/analyzer_plugin/test/plugin/completion_mixin_test.dart

Index: pkg/analyzer_plugin/test/plugin/completion_mixin_test.dart
diff --git a/pkg/analyzer_plugin/test/plugin/completion_mixin_test.dart b/pkg/analyzer_plugin/test/plugin/completion_mixin_test.dart
index 3626a8726699a0517f69fb759f56eccf62fc54d8..e4fa3e81b9a8cf6ed9a4def24c4dbf672bf1db7a 100644
--- a/pkg/analyzer_plugin/test/plugin/completion_mixin_test.dart
+++ b/pkg/analyzer_plugin/test/plugin/completion_mixin_test.dart
@@ -86,8 +86,7 @@ class _TestServerPlugin extends MockServerPlugin with CompletionMixin {
   }
 
   @override
-  List<CompletionContributor> getCompletionContributors(
-      AnalysisDriverGeneric driver) {
+  List<CompletionContributor> getCompletionContributors(String path) {
     return <CompletionContributor>[
       new _TestCompletionContributor(
           <CompletionSuggestion>[createSuggestion(), createSuggestion()]),
@@ -98,8 +97,7 @@ class _TestServerPlugin extends MockServerPlugin with CompletionMixin {
 
   @override
   Future<CompletionRequest> getCompletionRequest(
-      CompletionGetSuggestionsParams parameters,
-      covariant AnalysisDriverGeneric driver) async {
+      CompletionGetSuggestionsParams parameters) async {
     AnalysisResult result = new AnalysisResult(
         null, null, null, null, null, null, null, null, null, null, null);
     return new DartCompletionRequestImpl(