title: Flutter TapGestureRecognizer in text span not detect small words with different styles-- if it one or two characters
body: <p>i have a word like ABCDE each char in text span with different style  recognizer not detect correctly 
  EX:</p>
  
  <pre><code>recognizer: TapGestureRecognizer()
                    ..onTap = () =&gt; print('${char.key} onTap'), 
  </code></pre>
  
  <p>some of them not print accurate 
  but when all spans takes same style it works fine 
  Flutter Version 
  Flutter (Channel stable, v1.12.13+hotfix.9, on Microsoft Windows [Version 10.0.18362.720], locale
  en-US)</p>