[analysis_server] Fix missing dartdoc references in Library comments

Fixes https://github.com/dart-lang/sdk/issues/59946

Change-Id: I3b8558f72b6cc932f2c87ee4f2e993c5584907a7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/405361
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>

pkg/analysis_server/test/analysis/get_navigation_test.dart

@@ -211,6 +211,40 @@ final foo = {"key": ?Foo()};
     expect(target.length, 3);
   }
 
+  Future<void> test_documentation() async {
+    addTestFile('''
+/// [math]
+import 'dart:math' as math;
+''');
+    await waitForTasksFinished();
+    await _getNavigation(search: 'math]');
+    expect(regions, hasLength(1));
+    assertHasRegionString('math');
+    expect(testTargets, hasLength(1));
+    var target = targets[regions.first.targets.first];
+    expect(target.kind, ElementKind.PREFIX);
+    expect(target.offset, findOffset('math;'));
+    expect(target.length, 4);
+  }
+
+  Future<void> test_documentation_library() async {
+    addTestFile('''
+/// [math]
+library;
+
+import 'dart:math' as math;
+''');
+    await waitForTasksFinished();
+    await _getNavigation(search: 'math]');
+    expect(regions, hasLength(1));
+    assertHasRegionString('math');
+    expect(testTargets, hasLength(1));
+    var target = targets[regions.first.targets.first];
+    expect(target.kind, ElementKind.PREFIX);
+    expect(target.offset, findOffset('math;'));
+    expect(target.length, 4);
+  }
+
   Future<void> test_field_underscore() async {
     addTestFile('''
 class C {

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

@@ -438,6 +438,7 @@ class _DartNavigationComputerVisitor extends RecursiveAstVisitor<void> {
   @override
   void visitLibraryDirective(LibraryDirective node) {
     computer._addRegionForElement(node.name2, node.element2);
+    super.visitLibraryDirective(node);
   }
 
   @override