Fix PR886:

Fix PR886:
The result of yyparse() was not being checked. When YYERROR or YYABORT is
called it causes yyparse() to return 1 to indicate the error. The code was
silently ignoring this situation because it previously expected either an
exception or a null ParserResult to indicate an error. The patch corrects
this situation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30834 91177308-0d34-0410-b5e6-96231b3b80d8