[Support] Rewrite handleAllErrors in terms of cantFail.

This just switches handleAllErrors from using custom assertions that all errors
have been handled to using cantFail. This change involves moving some of the
class and function definitions around though.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311631 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed