swift234

Fix 28244-swift-valuedecl-isinstancemember.swift

Formerly we stopped type checking a PatternBindingDecl when it was marked
as invalid.  This prevented semantic analysis from doing things like expanding
"stored" properties in protocols into computed properties with getters and setter,
causing downstream problems.

Stop doing this, and instead do a bit of work to silence the downstream errors in
a more narrow way.