title: Toolbar doesn't show the overflow icon
body: <p>I'm using the new <code>Toolbar</code> instead of the <code>ActionBar</code>.
  On Android 5.0 everything is just fine:</p>
  
  <p><img src="https://i.stack.imgur.com/ht1pE.png" alt="enter image description here">
  On 4.4 it doesn't show the Overflow icon (though the function is there):</p>
  
  <p><img src="https://i.stack.imgur.com/04ziz.png" alt="enter image description here"></p>
  
  <p>This is the <code>toolbar.xml</code> I'm using:</p>
  
  <pre><code>&lt;android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      style="@style/HeaderBar"
      app:theme="@style/ActionBarThemeOverlay"
      app:popupTheme="@style/ActionBarPopupThemeOverlay"
      android:id="@+id/toolbar_actionbar"
      app:titleTextAppearance="@style/ActionBar.TitleText"
      app:contentInsetStart="?actionBarInsetStart"
      android:layout_width="match_parent"
      android:layout_height="?actionBarSize" /&gt;
  </code></pre>