Summary:
Aggregate initialization (e.g., `S s{1, 2}`) doesn't invoke a contructor.
Our frontend translates aggregation initialization as assigning to each field in the struct.
To avoid the appearance of the struct being uninitialized, count any assignment to a field of an aggregate struct as initializing the struct.
Reviewed By: jeremydubreil
Differential Revision: D7189671
fbshipit-source-id: ace02fc
Sam Blackshear