Remove redundant condition (PR28352) NFCI.

We were already testing is the op was not a leaf, so need to then test if it was a leaf (added it to the assert instead).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286817 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed