message: Allow index inside dimension tensors.
  Ever since MLIR now allows `index` type inside tensors, addressing this longstanding TODO.
diff: @@ -55,11 +55,10 @@ def HLO_Tuple : NestedTupleOf<[HLO_Tensor, HLO_Token]>;
  def HLO_TensorOrTuple : AnyTypeOf<[HLO_Tensor, HLO_Tuple]>;
  -// Dynamic representation of a shape vector as a tensor. Ideally this would be
  -// an index type (as it stores indices) but that is currently disallowed in
  -// MLIR.
  +// Dynamic representation of a shape vector as a tensor.
  def HLO_DimensionTensor : ShapedContainerType<
  - [AnySignlessInteger], And<[IsTensorTypePred, HasAnyRankOfPred<[1]>]>,
  + [Index, AnySignlessInteger],
  + And<[IsTensorTypePred, HasAnyRankOfPred<[1]>]>,
  "a 1D tensor of dimensions">;
  // In general, static shaped tensor constraints should be avoided unless
  