The only difference between deleteIfDeadInstruction and
RecursivelyDeleteTriviallyDeadInstructions is that the former also
manually invalidates SCEV. That's unnecessary because SCEV automatically
gets informed when an instruction is deleted via a ValueHandle. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228508 91177308-0d34-0410-b5e6-96231b3b80d8