Hi, good people... thanks your contributions for react-native, the amazing framework.

Now... I happen the issue, very headache...

react-native version: 0.47.1

Example, render the FlatList like this:

<FlatList
  ref="flatlist"
  ListHeaderComponent={one header component...}
/>

Maybe, the header component has a height such as 300.

When i execute scrollToEnd methods, i hope the list scroll to end, and the scroll distance should includes the header height (now 300).

But, it will scroll unexpected. the list will scroll to an uncertain position.

Based on my observation, it seemingly did not computed and included the header height.

Whether this is a bug or not ? How can i solve it in current version ?