message: Add an escape path for people to skip dynamic padding in TPUStrategy.
  In the case where a dynamic op is not support by XLA, we want people
  to be able to opt out dynamic padding.
diff: @@ -218,6 +218,7 @@ class TPUExtended(distribute_lib.StrategyExtendedV1):
  self._require_static_shapes = True
  self.experimental_enable_get_next_as_optional = True
  + self.experimental_enable_dynamic_batch_size = True
  def _validate_colocate_with_variable(self, colocate_with_variable):
  values.validate_colocate(colocate_with_variable, self)
  @@ -656,7 +657,7 @@ class TPUExtended(distribute_lib.StrategyExtendedV1):
  # Construct and pass `maximum_shapes` so that we could support dynamic
  # shapes using dynamic padder.
  - if replicate_inputs:
  + if self.experimental_enable_dynamic_batch_size and replicate_inputs:
  maximum_shapes = []
  flattened_list = nest.flatten(replicate_inputs[0])
  for input_tensor in flattened_list:
  