Summary:
A component can be backed by native "node" that can change its internal state, which would result in a new UI after the next layout. Since js has no way of knowing that this has happened it wouldn't trigger a layout if nothing in js world has changed. Therefore we need a way how to trigger layout from native code.
This diff does it by adding methods `layoutIfNeeded` on the uimanager and `isBatchActive` on the bridge.
When `layoutIfNeeded` is called it checks whether a batch is in progress. If it is we do nothing, since at it's end layout happens. If a batch is not in progress we immidiately do layout.
I went with the easiest way how to implement this - `isBatchActive` is a public method on the bridge. It's not ideal, but consistent with other methods for modules.
public
Reviewed By: jspahrsummers, nicklockwood
Differential Revision: D2748896
fb-gh-sync-id: f3664c4af980d40a463b538e069b26c9ebad6300
a86171a482