Experimental `getDiagnostics` request (#24480).

pkg/analysis_server/tool/spec/from_html.dart

Index: pkg/analysis_server/tool/spec/from_html.dart
diff --git a/pkg/analysis_server/tool/spec/from_html.dart b/pkg/analysis_server/tool/spec/from_html.dart
index 70c5a44378efc8856ba5a07915f145bc8588cea0..2ff2fe846d26aceaf3e59ef005a7cdbe18f6f1de 100644
--- a/pkg/analysis_server/tool/spec/from_html.dart
+++ b/pkg/analysis_server/tool/spec/from_html.dart
@@ -140,7 +140,8 @@ Domain domainFromHtml(dom.Element html) {
   String name = html.attributes['name'];
   String context = name ?? 'domain';
   bool experimental = html.attributes['experimental'] == 'true';
-  checkAttributes(html, ['name'], context, optionalAttributes: ['experimental']);
+  checkAttributes(html, ['name'], context,
+      optionalAttributes: ['experimental']);
   List<Request> requests = <Request>[];
   List<Notification> notifications = <Notification>[];
   recurse(html, context, {
@@ -151,7 +152,8 @@ Domain domainFromHtml(dom.Element html) {
       notifications.add(notificationFromHtml(child, context));
     }
   });
-  return new Domain(name, experimental, requests, notifications, html);
+  return new Domain(name, requests, notifications, html,
+      experimental: experimental);
 }
 
 dom.Element getAncestor(dom.Element html, String name, String context) {
@@ -421,9 +423,10 @@ TypeDefinition typeDefinitionFromHtml(dom.Element html) {
   checkName(html, 'type');
   String name = html.attributes['name'];
   String context = name != null ? name : 'type';
-  checkAttributes(html, ['name'], context);
+  checkAttributes(html, ['name'], context, optionalAttributes: ['experimental']);
   TypeDecl type = processContentsAsType(html, context);
-  return new TypeDefinition(name, type, html);
+  bool experimental = html.attributes['experimental'] == 'true';
+  return new TypeDefinition(name, type, html, experimental: experimental);
 }
 
 /**
@@ -514,14 +517,15 @@ TypeObjectField typeObjectFieldFromHtml(dom.Element html, String context) {
  * Create a [TypeObject] from an HTML description.
  */
 TypeObject typeObjectFromHtml(dom.Element html, String context) {
-  checkAttributes(html, [], context);
+  checkAttributes(html, [], context,  optionalAttributes: ['experimental']);
   List<TypeObjectField> fields = <TypeObjectField>[];
   recurse(html, context, {
     'field': (dom.Element child) {
       fields.add(typeObjectFieldFromHtml(child, context));
     }
   });
-  return new TypeObject(fields, html);
+  bool experimental = html.attributes['experimental'] == 'true';
+  return new TypeObject(fields, html, experimental: experimental);
 }
 
 /**