[DAS] Fixes Go To Definition and occurrences for extension type parameter

Fixes: #63898
Fixes: #63910
Change-Id: I1a07522926c25641ccda8230451ff6403b17ed46
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/528300
Reviewed-by: Keerti Parthasarathy <keertip@google.com>
Commit-Queue: Keerti Parthasarathy <keertip@google.com>
Auto-Submit: FMorschel <git@fmorschel.dev>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>

Author: FMorschel

pkg/analysis_server/lib/src/domains/analysis/occurrences_dart.dart

@@ -283,7 +283,7 @@ class DartUnitOccurrencesComputerVisitor extends GeneralizingAstVisitor<void> {
       return;
     }
 
-    var element = node.writeOrReadElement;
+    var element = node.writeOrReadElement?.baseElement;
     if (element != null) {
       _addOccurrence(element, node.token);
     }

pkg/analysis_server/test/analysis/notification_occurrences_test.dart

@@ -318,6 +318,14 @@ void f(E e) {
 ''');
   }
 
+  Future<void> test_extensionType_parameter() async {
+    await assertOccurrences(kind: ElementKind.FIELD, '''
+extension type E(int /*[0*/it/*0]*/) {
+  int get value => /*[1*/it/*1]*/;
+}
+''');
+  }
+
   Future<void> test_extensionType_setter() async {
     await assertOccurrences(kind: ElementKind.SETTER, '''
 extension type E(int it) {

pkg/analysis_server/test/lsp/definition_test.dart

@@ -517,6 +517,30 @@ class A {
     await testContents(contents);
   }
 
+  Future<void> test_constructor_newImplicit() async {
+    var contents = '''
+class [!WithGeneric!]<T> {}
+
+void fn() {
+  final val = WithGeneric<String>.n^ew();
+}
+''';
+
+    await testContents(contents);
+  }
+
+  Future<void> test_constructor_newImplicit_dotShorthands() async {
+    var contents = '''
+class [!WithGeneric!]<T> {}
+
+void fn() {
+  final WithGeneric<String> val = .n^ew();
+}
+''';
+
+    await testContents(contents);
+  }
+
   Future<void> test_constructor_redirectingSuper_wildcards() async {
     var contents = '''
 class A {
@@ -662,6 +686,26 @@ extension [!StringExtension!] on String {
     await testContents(contents);
   }
 
+  Future<void> test_extensionType_parameter() async {
+    var contents = '''
+extension type E(int [!it!]) {
+  int get value => it^;
+}
+''';
+
+    await testContents(contents);
+  }
+
+  Future<void> test_extensionType_parameter_ofTypeParameter() async {
+    var contents = '''
+extension type E<T>(T [!it!]) {
+  T get value => it^;
+}
+''';
+
+    await testContents(contents);
+  }
+
   Future<void> test_field_underscore() async {
     var contents = '''
 class A {

pkg/analysis_server/test/lsp/document_highlights_test.dart

@@ -600,6 +600,17 @@ void f(E e) {
     );
   }
 
+  Future<void> test_extensionType_parameter() async {
+    await _testMarkedContent(
+      '''
+extension type E(int /*[0*/it/*0]*/) {
+  int get value => /*[1*/it/*1]*/;
+}
+''',
+      kinds: {0: .Write, 1: .Read},
+    );
+  }
+
   Future<void> test_extensionType_setter() async {
     await _testMarkedContent('''
 extension type E(int it) {

pkg/analyzer_plugin/lib/src/utilities/navigation/navigation_dart.dart

@@ -699,7 +699,7 @@ class _DartNavigationComputerVisitor extends RecursiveAstVisitor<void> {
 
   @override
   void visitSimpleIdentifier(SimpleIdentifier node) {
-    var element = node.writeOrReadElement;
+    var element = node.writeOrReadElement?.baseElement;
     if (element case PrefixElement(:var fragments, :var name)) {
       for (var fragment in fragments) {
         computer._addRegionForFragmentRange(