This fixes two bugs related to string-casting in React:
# Setting `<input value={0} />` would use an empty `value` because `0` is falsey.
# Using `onChange` and `setState` with non-strings could lead to an infinite loop.
The latter is possible with controlled inputs when:
- User changes input value.
- `onpropertychange` fires.
- `ChangeEventPlugin` dispatches `onChange`.
- A handler responds via `this.setState` with a non-string value (e.g. a number).
- The input re-renders and re-sets `value`.
- The new `value` is not a string, but the current `value` (read from the element) is cast to a string automatically by the browser.
- This triggers another `onpropertychange`.
- `ChangeEventPlugin` dispatches another `onChange`.
- ...
This is a bit unfortunate, but it'll shut lint up for the time being. We
can't just change the modules to use `module.exports = { ... }` due to
how we handle circular dependencies internally (`ReactMount` require
`ReactID` and vice versa).
When each component unmounts, it already cleans up its respective entry in the node cache. Let's stop blowing away the entire node cache unnecessarily.
This should improve performance because a React component's root will never need to be searched for more than once.
This is a micro-optimization that reduces the lookup time for missing lifecycle methods. The extra amount of memory is linear to the number of components that exist on a page which I think is a worthwile trade-off.
When `ReactNativeComponent` updates, it calls `updatePropertyByID` in `ReactDOMIDOperations` which calls `DOMPropertyOperations`. However, in `ReactDOMIDOperations`, we will lookup the node for an ID using `ReactID.getNode`. This wastes time looking for nodes when we may not need to ever update it (e.g. `children`).
This changes `ReactNativeComponent` to bail out sooner.
