[analyzer] Fix wrong .run call in lsp completion handler; add timing to sendResponse

E.g. when sending 2000 results to a completion request, sending (json
and utf8 encoding) can be a very big part of the cost and it's very
confusing having it attributed to "self" in "request".
Also `mapSuggestions` looked much cheaper than it was because it used
`run` instead of `runAsync`.

Change-Id: Ifd219adb25fa658930548536eb8eb46276acd4a2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/436922
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Jens Johansen <[email protected]>

Author: jensjoha

pkg/analysis_server/lib/src/lsp/handlers/handler_completion.dart

@@ -549,7 +549,7 @@ class CompletionHandler
         );
       }
 
-      var rankedResults = await performance.run('mapSuggestions', (
+      var rankedResults = await performance.runAsync('mapSuggestions', (
         performance,
       ) async {
         var completionItems = <({CompletionItem item, double score})>[];

pkg/analysis_server/lib/src/lsp/lsp_analysis_server.dart

@@ -1067,11 +1067,14 @@ class LspAnalysisServer extends AnalysisServer {
     );
     result.ifError((error) => sendErrorResponse(message, error));
     result.ifResult(
-      (result) => sendResponse(
-        ResponseMessage(
-          id: message.id,
-          result: result,
-          jsonrpc: jsonRpcVersion,
+      (result) => messageInfo.performance.run(
+        'sendResponse',
+        (_) => sendResponse(
+          ResponseMessage(
+            id: message.id,
+            result: result,
+            jsonrpc: jsonRpcVersion,
+          ),
         ),
       ),
     );