[turbofan] add non fixed slot constraint to register allocator

test/unittests/compiler/instruction-sequence-unittest.cc

Index: test/unittests/compiler/instruction-sequence-unittest.cc
diff --git a/test/unittests/compiler/instruction-sequence-unittest.cc b/test/unittests/compiler/instruction-sequence-unittest.cc
index 3fed64e27d65c5571eb8882ab2c7ccb1d1f19074..af9e4733f8874932acb95bce09fb3365915c7e6a 100644
--- a/test/unittests/compiler/instruction-sequence-unittest.cc
+++ b/test/unittests/compiler/instruction-sequence-unittest.cc
@@ -373,6 +373,9 @@ InstructionOperand InstructionSequenceTest::ConvertInputOp(TestOperand op) {
     case kRegister:
       return Unallocated(op, UnallocatedOperand::MUST_HAVE_REGISTER,
                          UnallocatedOperand::USED_AT_START);
+    case kSlot:
+      return Unallocated(op, UnallocatedOperand::MUST_HAVE_SLOT,
+                         UnallocatedOperand::USED_AT_START);
     case kFixedRegister:
       CHECK(0 <= op.value_ && op.value_ < num_general_registers_);
       return Unallocated(op, UnallocatedOperand::FIXED_REGISTER, op.value_);