`allocClassWithName` allocates an object with the given type.
The type is actually provided as a string argument (type's name).
This creates a possibility for not particularly useful warnings
from the analyzer.
In order to combat with those, this patch checks for casts of the
`allocClassWithName` results to types mentioned directly as its
argument. All other uses of this method should be reasoned about
as before.
rdar://72165694
Differential Revision: https://reviews.llvm.org/D99500
Valeriy Savchenko