Revert "Cleanup some SCEV logic a bit."

This reverts commit 82cd8f7382322bee7a71cdc31f7a923c44d37d32.

Just add a comment instead!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177377 91177308-0d34-0410-b5e6-96231b3b80d8