message: Check type directly instead of trying to check element type
  Previously this attempted to check the element type, but NoneType does not have
  an element type and so it didn't behave as expected. Swapping to TypeIs
  checking instead.
diff: @@ -174,12 +174,6 @@ def TFL_StatefulTensor : TypeAlias<AnyTensor, "stateful tensor">;
  class TFL_TensorOfOrNone<list<Type> allowedTypes, string description = ""> :
  AnyTypeOf<[TensorOf<allowedTypes>, NoneType], description>;
  -// Type Constraint operand `idx`'s type is NOT `type`.
  -// TODO(b/131936589): Once this bug is fixed, we should be able to use
  -// Neg<TCopVTEtIs<idx, NoneType>>> and can remove this.
  -class TFL_TCopIsNot<int idx, Type type> :
  - Neg<CPred<"$_op.getOperand(" # idx # ")->getType().isa<" # type # ">()">>;
  -
  def TFL_FpOrI32OrI64Tensor : TensorOf<[AnyFloat, TFL_Int32Or64]>;
  //===----------------------------------------------------------------------===//
  @@ -2549,7 +2543,7 @@ def LstmProjectionWeightBiasConstraint : PredOpTrait<
  "projection bias must not be specified",
  Or<[
  And<[TCopVTEtIs<16, NoneType>, TCopVTEtIs<17, NoneType>]>,
  - TFL_TCopIsNot<16, NoneType>]>>;
  + Neg<TypeIsPred<"projection_weights", NoneType>>]>>;
  // TODO(b/137798843): Need to add two additional constraints for both LSTM and
  // UnidirectionalSequenceLstm
  