7175911: Simplify error reporting API in Check.CheckContext interfaceSummary: Make error messages generated during Check.checkType more uniform and more scalableReviewed-by: jjg, dlsmith
7151492: Encapsulate check logic into Attr.ResultInfoSummary: ResultInfo class should be used to make attribution code transparent w.r.t. check logic being usedReviewed-by: jjg, dlsmith
6979683: inconsistent interaction of reference cast with box/unbox conversions leaves out a useful caseSummary: Allow casts which narrow and then unbox.Reviewed-by: mcimadamore