TextInput with prompt displays black prompt

The reason of the bug is component visibility changes without data changes.

Steps to reproduce (the easiest way to reproduce, but bug persists almost everywhere):
1. Create AIR application (add mobilecomponents.swc).
2. Add CalloutButton
3. Add spark TextInput inside CalloutButton with some prompt text.
4. Run. Click on CalloutButton -> grey prompt in TextInput.
5. Close and open CalloutButton second time -> black color for prompt

Code:
<s:CalloutButton label="TEST">
<s:TextInput prompt="SOME PROMPT" />
</s:CalloutButton>