Issue 20240. Use a FileManager that manages its own temporary directory.

pkg/analysis_server/lib/src/analysis_server.dart

Index: pkg/analysis_server/lib/src/analysis_server.dart
diff --git a/pkg/analysis_server/lib/src/analysis_server.dart b/pkg/analysis_server/lib/src/analysis_server.dart
index 995de16eb9e90f5fd32886a1cd4f71cd05f3037d..02091944f6bd6be1bc4b8a6a8c048d7316b906d9 100644
--- a/pkg/analysis_server/lib/src/analysis_server.dart
+++ b/pkg/analysis_server/lib/src/analysis_server.dart
@@ -693,6 +693,14 @@ class AnalysisServer {
     }
   }
 
+  void shutdown() {
+    running = false;
+    if (index != null) {
+      index.clear();
+      index.stop();
+    }
+  }
+
   /**
    * Return the [CompilationUnit] of the Dart file with the given [path].
    * Return `null` if the file is not a part of any context.