- Have TryStaticImplicitCast set the cast kind to NoOp when binding a...

- Have TryStaticImplicitCast set the cast kind to NoOp when binding a reference. CheckReferenceInit already inserts implicit casts to the necessary types. This fixes an assertion in CodeGen for some casts and brings a fix for PR5453 close, if I understand that bug correctly.
- Also, perform calculated implicit cast sequences if they're determined to work. This finally diagnoses static_cast to ambiguous or implicit bases and fixes two long-standing fixmes in the test case. For the C-style cast, this requires propagating the access check suppression pretty deep into other functions.
- Pass the expressions for TryStaticCast and TryStaticImplicitCast by reference. This should lead to a better AST being emitted for such casts, and also fixes a memory leak, because CheckReferenceInit and PerformImplicitConversion wrap the node passed to them. These wrappers were previously lost.

llvm-svn: 88809