[NFC][IR] PHINode: ... and assert in another ctor too

llvm/include/llvm/IR/Instructions.h

@@ -2592,6 +2592,7 @@ class PHINode : public Instruction {
           BasicBlock *InsertAtEnd)
     : Instruction(Ty, Instruction::PHI, nullptr, 0, InsertAtEnd),
       ReservedSpace(NumReservedValues) {
+    assert(!Ty->isTokenTy() && "PHI nodes cannot have token type!");
     setName(NameStr);
     allocHungoffUses(ReservedSpace);
   }