message: [XLA] Don't dump the "contents" of constants with a zero-sized dimension in the HLO graph dumper.
  Previously we'd dump e.g. "{ {}, {}, ... }" for an f32[100, 0], which is
  just noise.
diff: @@ -782,6 +782,14 @@ string HloDotDumper::GetInstructionNodeInlinedOperands(
  auto stringify_constant = [](const HloInstruction* constant) {
  const auto& shape = constant->shape();
  + // If the shape has a dimension of size zero, print it as e.g.
  + // "{} (f32[42, 0, 10])". The alternative, calling Literal::ToString(),
  + // enumerates all of its empty dimensions (e.g. "{ { {}, {} }, ..."), which
  + // is just noise.
  + if (ShapeUtil::HasZeroElements(shape)) {
  + return Printf("{} (%s)", ShapeUtil::HumanString(constant->shape()));
  + }
  +
  // Print the literal value of constants with <= K elements.
  optional<int64> elem_count;
  if (!ShapeUtil::IsOpaque(shape) && !ShapeUtil::IsTuple(shape)) {
  