Summary:
LocalData might be used to communicate some infomation between `ShadowNode`s
and native component views.
We will use it soon to store (and transmit to mounting layer) prepared for rendering attributed text in Text component.
Reviewed By: mdvacca
Differential Revision: D7738582
fbshipit-source-id: 1ead23ffd105cce0b3d9aeb9fc1d0df47673be50
