Fix two small bugs in typo correction. One assertion failure building member...

Fix two small bugs in typo correction. One assertion failure building member expressions because the lookup finds a different name than the original, fixed by updating the LookupResult's name with the name of the found decl. Second is that we also diagnose delayed typo exprs in the index of an array subscript expression.

The testcase shows a third bug with a FIXME in it.

llvm-svn: 224183