Revert "Reapply commit r258404 with fix"

This commit exposes a crash in computeKnownBits on the Chromium buildbots.
Reverting to investigate.

Reference: https://llvm.org/bugs/show_bug.cgi?id=26307

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@258812 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed