Summary:
This is a small cleanup to move initialization out of the `constructor` as it is unnecessary, and it is currently double initializing a few values.
Changelog:
[General][Changed] Clean up the initialization of instance variables in ScrollView
Reviewed By: nadiia
Differential Revision: D27631320
fbshipit-source-id: 762277e4993a9ce86d444ff2d9e845c93e94d1a8