Crash even less on malformed attributes in an incorrect location.

This is a follow-up to r224915.  This adds a bit more line noise to the tests
added in that revision to make sure the parser is ready for a toplevel decl
after each incorrect line.  Use this to move the tests up to where they belong.
This uncovered that the early return was missing a call to
ActOnTagDefinitionError(), so add that. (Also fixes at least one of the crashes
on SLi's bot.)

llvm-svn: 224958