Fix memoizeWrap when displayName is null (#654)

`Component.displayName` can be undefined for release builds which means a bunch of components will fight for the undefined key. In my app it results in the `Switch` component rendering nothing (or probably just another component like `ScrollView`). I also added a null check since some components are being removed from RN core like ToolbarAndroid so it makes `memoizeWrap` safe in those cases.

GestureComponents.js

@@ -3,17 +3,21 @@ import ReactNative from 'react-native';
 
 import createNativeWrapper from './createNativeWrapper';
 
-const MEMOIZED = {};
+const MEMOIZED = new WeakMap();
 
 function memoizeWrap(Component, config) {
- const memoized = MEMOIZED[Component.displayName];
- if (memoized) {
- return memoized;
+ if (Component == null) {
+ return null;
  }
- return (MEMOIZED[Component.displayName] = createNativeWrapper(
- Component,
- config
- ));
+ let memoized = MEMOIZED.get(Component);
+ if (!memoized) {
+ memoized = createNativeWrapper(
+ Component,
+ config
+ );
+ MEMOIZED.set(Component, memoized);
+ }
+ return memoized;
 }
 
 module.exports = {