swift234

two changes: 

1) Teach resolveImmutableBase about SubscriptExprs that have 
resolved the decl that they are referring to.  This fixes case where we'd
generate an imprecise diagnostic because we weren't able to find the
result in the ResolvedOverloadSet list (which is because CSApply rewrite
it to a different expr node and the locator can't find it).

2) Change FailureDiagnosis::typeCheckIndependentSubExpression to have a
   blacklist of expressions that aren't recursed into, along with rationale
   for each node kind, instead of a short white list.  This produces more
   predictable results, e.g. producing the right diagnostic in 
   ClangModules/objc_parse.swift



Swift SVN r30118