Summary:
In some cases, the accessibilityLabel contains a leading space. This is because `RCTRecursiveAccessibilityLabel` adds a space before every iteration of the loop including the first.
After this change, the contract is that:
- `RCTRecursiveAccessibilityLabel` always returns a string with a leading space.
- `accessibilityLabel` never returns a string with a leading space.
**Test plan**
I created a test app with the following code:
```
<View style={{height: 100, width: 100, backgroundColor: 'steelblue'}} accessible={true}>
<View style={{height: 20, width: 20, backgroundColor: 'red'}} accessibilityLabel='One' />
<View style={{height: 20, width: 20, backgroundColor: 'yellow'}} accessibilityLabel='Two' />
<View style={{height: 20, width: 20, backgroundColor: 'green'}} accessibilityLabel='Three' />
</View>
```
Before this change, the accessibilityLabel of the outermost View was " One Two Three" (notice the leading space).
After this change, it is "One Two Three" as desired.
Adam
Closes https://github.com/facebook/react-native/pull/12269
Reviewed By: javache
Differential Revision: D4596761
Pulled By: shergin
fbshipit-source-id: 7d5ff704e858d9f277d1547339a2831ffa90f592
6fbc2c9972