Summary:
The new interface of ComponentDescriptor makes ShadowNode creation/cloning process a bit more explicit:
Now customers (UIManager) must prepare Props object explicitly before creation or cloning.
Besides general clarity, we need this to prepare for a new virtual `ShadowNode::clone()` method which will serve "virtual constructor" role,
redirecting execution to concrete ComponentDescriptor instance.
Actually, the whole purpose of concrete ComponentDescriptor instance is serve "virtual constructor" role (and all this code should be "templated").
Reviewed By: mdvacca
Differential Revision: D7591714
fbshipit-source-id: 8793b3ef70ed7ae113efb36ad1eee20573360dc8
3fd2e2da4f