Revert "[TableGen] Use cast instead of dyn_cast where result isn't checked before being dereferenced."

Turns out I misread the parentheses. Though I'm pretty sure its always a RecordRecTy and non of the callers really seem to expect null. But until I'm completely sure I'm going to revert this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235469 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed