Summary:
Remove layout-only views. Works by checking properties against a list of known properties that only affect layout. The `RCTShadowView` hierarchy still has a 1:1 correlation with the JS nodes.
This works by adjusting the tags and indices in `manageChildren`. For example, if JS told us to insert tag 1 at index 0 and tag 1 is layout-only with children whose tags are 2 and 3, we adjust it so we insert tags 2 and 3 at indices 0 and 1. This keeps changes out of `RCTView` and `RCTScrollView`. In order to simplify this logic, view moves are now processed as view removals followed by additions. A move from index 0 to 1 is recorded as a removal of view at indices 0 and 1 and an insertion of tags 1 and 2 at indices 0 and 1. Of course, the remaining indices have to be offset to take account for this.
The `collapsible` attribute is a bit of a hack to force `RCTScrollView` to always have one child. This was easier than rethinking out the logic there, but we could change this later.
@public
Test Plan: There are tests in `RCTUIManagerTests.m` that test the tag- and index-manipulation logic works. There are various scenarios including add-only, remove-only, and move. In addition, two scenario tests verify that the optimization works by checking the number of views and shadow views after various situations happen.
- [ReactNative] Use deprecated ix in TabBarExample | Amjad Masad
- [ReactNative] Expanded license on obj-c files | Christopher Chedeau
- [ReactNative] Expanded license on js files | Christopher Chedeau
- [ReactNative] Fix React Devtools integration | Alex Kotliarskyi
- [Text] Account for font leading so descenders are not clipped | James Ide
- [ReactNative] Expanded license on js packager files | Christopher Chedeau
- more UIExplorer flow | Basil Hosmer
- [react-packager] Pick up package changes while running | Amjad Masad
- Added a graph view and a ReactNative metric that displays current queue and execution time for the JS thread. | Bryce Redd
- [ReactNative] Add NativeModules and DeviceEventEmitter to react-native exports | Alex Kotliarskyi
- [react-packager] transformModulePath option is not actually required | Amjad Masad
- Implement TextInput.clearButtonMode added by D1875684 on OSS fork + example | Tadeu Zagallo
- [ReactNative] Use local CocoaPod config for ReactNative modules | Spencer Ahrens
- [ReactNative] Pull out some OSS modules into separate libs | Spencer Ahrens
- Enqueue events at 60fps + profiling helpers | Tadeu Zagallo
