message: Improve error message of strided slice op.
diff: @@ -223,12 +223,10 @@ class StridedSliceOp : public XlaOpKernel {
  input_elements_sliced *= input_shape.dim_size(d);
  }
  - OP_REQUIRES(
  - ctx, output_elements == input_elements_sliced,
  + OP_REQUIRES(ctx, output_elements == input_elements_sliced,
  errors::InvalidArgument(
  - "The number of output elements ", output_elements,
  - " has to equal to number of input elements that are sliced ",
  - input_elements_sliced, " when input indices are not constant."));
  + "Dynamic indices of strided_slice_op have to be leading "
  + "dimensions in the indices list."));
  for (int64 i = 0; i < ctx->InputShape("begin").dims(); ++i) {
  OP_REQUIRES(
  