Revert "[MLIR] getBackwardSlice: don't bail on ops that are IsolatedFromAbove"#160160

IanWood1 wants to merge 1 commit intomainllvm/llvm-project:mainfrom

revert-158135-fix_getbackwardslicellvm/llvm-project:revert-158135-fix_getbackwardsliceCopy head branch name to clipboard