title: Explict generic type in function by default replace this type to dynamic inside
body: <p>Why explict generic type in function by default replace this type to dynamic inside?</p>
  <p>example:</p>
  <pre class="lang-dart prettyprint-override"><code>class Boo {
    void displayType&lt;int&gt;() {
      print('type int to string: $int');
      print('type string to string: $String');
    }
  }
  
  main() {
    final boo = Boo();
    boo.displayType();
  }
  
  </code></pre>
  <p>output:</p>
  <pre><code>type int to string: dynamic
  type string to string: String
  </code></pre>
  <p>its bug?</p>