title: Flutter - SingleChildScrollView not scrollable inside SizeTransition
body: <p>As the title suggests, I'm trying to create a container that can expand with SizeTransition. After the container is expanded, the user will enter some texts and it will lead to bottom overflow. So I use SingleChildScrollView. However, the container doesn't seem to be scrollable and overflow still occurs.</p>
  <p>Below is part of my code.</p>
  <pre class="lang-dart prettyprint-override"><code>Widget _buildComponentA() {
      return Column(
        children: &lt;Widget&gt;[
          Row(
            children: &lt;Widget&gt;[
            //some widgets
            ],
          ),
          SizeTransition(
            child: Container(
              child: SingleChildScrollView(
                child: Column(
                  children: &lt;Widget&gt;[
                  //some widgets
                  ],
                ),
              ),
            ),
            sizeFactor: _expand,
          ),
        ],
      );
    }
  </code></pre>
  <p>The <code>_expand</code> variable is defined as follows.</p>
  <pre class="lang-dart prettyprint-override"><code>_expandController = AnimationController(
        duration: Duration(milliseconds: 500),
        vsync: this,
  );
  _expandAnimation = Tween&lt;double&gt;(begin: 0.0, end: 1.0).animate(_expandController);
  </code></pre>
  <p>Thanks!</p>