Summary:
`RCTFontTests` test in RNTester is broken if the target deployment is <= OS 8.2. This is because RCTFont.mm overrides the OS-defined values, but the override is only visible to RCTFont.mm internals. As the result, when the Unit test tries to create UIFont of the "same" weight, it got a different font - most likely due to internal floating rounding errors.
To mitigate, code that wants to test out internals of RCTFont should import RCTFontConstantsOverride.h
Reviewed By: mmmulani
Differential Revision: D7900954
fbshipit-source-id: e5814ef059a8afdfb5205ca1af46c41b3cfd4318
6611fefef7