Fix a bug in textDocument/definition for primary constructors

Change-Id: Id24cdfda1c84322b5fa77cca0c87df0784482ec6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/506080
Commit-Queue: Samuel Rawlins <srawlins@google.com>
Auto-Submit: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Samuel Rawlins <srawlins@google.com>

pkg/analysis_server/lib/src/utilities/navigation/keyword_navigation_computer.dart

@@ -65,9 +65,12 @@ class KeywordNavigationComputer {
       MethodDeclaration() => function.name,
       ConstructorDeclaration() =>
         // For named constructors, return the name.
-        // For unnamed constructors, use the return type / class name.
-        // TODO(scheglov): support primary constructors
-        function.name ?? function.typeName!.beginToken,
+        // For unnamed constructors, use the return type / class name, or the
+        //  `new` or `factory` keyword.
+        function.name ??
+            function.typeName?.beginToken ??
+            function.newKeyword ??
+            function.factoryKeyword,
       _ => null,
     };
   }

pkg/analysis_server/test/lsp/definition_test.dart

@@ -1057,6 +1057,31 @@ class MyClass {
     await testContents(contents);
   }
 
+  Future<void> test_keywordNavigation_return_toConstructor_withFactory() async {
+    var contents = '''
+class MyClass {
+  [!factory!] () {
+    ret^urn MyClass.n();
+  }
+  MyClass.n();
+}
+''';
+
+    await testContents(contents);
+  }
+
+  Future<void> test_keywordNavigation_return_toConstructor_withNew() async {
+    var contents = '''
+class MyClass {
+  [!new!] () {
+    ret^urn;
+  }
+}
+''';
+
+    await testContents(contents);
+  }
+
   Future<void> test_keywordNavigation_return_toFunction() async {
     var contents = '''
 int [!foo!]() {