Move diagnostics to `diagnostics` domain (#24931).

pkg/analysis_server/test/integration/protocol_matchers.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 //
 // This file has been automatically generated.  Please do not edit it manually.
 // To regenerate the file, use the script
 // "pkg/analysis_server/tool/spec/generate_files".
 
 /**
  * Matchers for data types defined in the analysis server API
@@ skipping 989 matching lines @@
  */
 final Matcher isExecutionLaunchDataParams = new LazyMatcher(() => new MatchesJsonObject(
   "execution.launchData params", {
     "file": isFilePath
   }, optionalFields: {
     "kind": isExecutableKind,
     "referencedFiles": isListOf(isFilePath)
   }));
 
 /**
- * experimental.getDiagnostics params
+ * diagnostic.getDiagnostics params
  */
-final Matcher isExperimentalGetDiagnosticsParams = isNull;
+final Matcher isDiagnosticGetDiagnosticsParams = isNull;
 
 /**
- * experimental.getDiagnostics result
+ * diagnostic.getDiagnostics result
  *
  * {
  *   "contexts": List<ContextData>
  * }
  */
-final Matcher isExperimentalGetDiagnosticsResult = new LazyMatcher(() => new MatchesJsonObject(
-  "experimental.getDiagnostics result", {
+final Matcher isDiagnosticGetDiagnosticsResult = new LazyMatcher(() => new MatchesJsonObject(
+  "diagnostic.getDiagnostics result", {
     "contexts": isListOf(isContextData)
   }));
 
 /**
  * AddContentOverlay
  *
  * {
  *   "type": "add"
  *   "content": String
  * }
@@ skipping 1414 matching lines @@
  *
  * {
  *   "newName": String
  * }
  */
 final Matcher isRenameOptions = new LazyMatcher(() => new MatchesJsonObject(
   "rename options", {
     "newName": isString
   }));