[analyzer] Fix handling of annotated vars/fields in api.txt.

Changes the tool that generates `api.txt` files for the analyzer (and
related packages) so that when examining a synthetic element, it looks
for annotations on the corresponding non-synthetic element.

This fixes detection of `@deprecated` and `@experimental` on getters
and setters induced by top level variables and fields.

Addresses
https://dart-review.googlesource.com/c/sdk/+/455820/comment/f2a39140_563a86de/.

Change-Id: I6a6a6964c06905fc94b27a48a150cb2430afad99
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/456320
Reviewed-by: Brian Wilkerson <[email protected]>
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Paul Berry <[email protected]>

Author: stereotype441

pkg/analyzer/api.txt

@@ -578,8 +578,8 @@ package:analyzer/dart/analysis/utilities.dart:
   parseString (function: ParseStringResult Function({required String content, FeatureSet? featureSet, String? path, bool throwIfDiagnostics}))
   resolveFile (function: Future<SomeResolvedUnitResult> Function({required String path, ResourceProvider? resourceProvider}))
 package:analyzer/dart/ast/ast.dart:
-  useDeclaringConstructorsAst (static getter: bool)
-  useDeclaringConstructorsAst= (static setter: bool)
+  useDeclaringConstructorsAst (static getter: bool, experimental)
+  useDeclaringConstructorsAst= (static setter: bool, experimental)
   AdjacentStrings (class extends Object implements StringLiteral):
     strings (getter: NodeList<StringLiteral>)
   AnnotatedNode (class extends Object implements AstNode):

pkg/analyzer_utilities/lib/tool/api.dart

@@ -402,10 +402,14 @@ class ApiDescription {
         throw UnimplementedError('Unexpected element: $runtimeType');
     }
 
-    if (element.metadata.hasDeprecated) {
+    // For synthetic elements such as getters/setters induced by top level
+    // variables and fields, annotations can be found on the corresponding
+    // non-synthetic element.
+    var nonSyntheticElement = element.nonSynthetic;
+    if (nonSyntheticElement.metadata.hasDeprecated) {
       parentheticals.add(['deprecated']);
     }
-    if (element.metadata.hasExperimental) {
+    if (nonSyntheticElement.metadata.hasExperimental) {
       parentheticals.add(['experimental']);
     }