Add recognizer compatibility API (#34086)

packages/flutter/lib/src/painting/inline_span.dart

@@ -5,6 +5,7 @@
 import 'dart:ui' as ui show ParagraphBuilder;
 
 import 'package:flutter/foundation.dart';
+import 'package:flutter/gestures.dart';
 
 import 'basic_types.dart';
 import 'text_painter.dart';
@@ -102,6 +103,11 @@ abstract class InlineSpan extends DiagnosticableTree {
   @Deprecated('InlineSpan does not innately have children. Use TextSpan.children instead.')
   List<InlineSpan> get children => null;
 
+  /// Returns the [GestureRecognizer] associated with this span if this is an
+  /// instance of [TextSpan], otherwise returns null.
+  @Deprecated('InlineSpan does not innately have a recognizer. Use TextSpan.recognizer instead.')
+  GestureRecognizer get recognizer => null;
+
   /// Apply the properties of this object to the given [ParagraphBuilder], from
   /// which a [Paragraph] can be obtained.
   ///

packages/flutter/lib/src/painting/text_span.dart

@@ -170,6 +170,7 @@ class TextSpan extends InlineSpan {
   /// }
   /// ```
   /// {@end-tool}
+  @override
   final GestureRecognizer recognizer;
 
   /// An alternative semantics label for this [TextSpan].