message: Reduce Layer.__call__ overhead by ~5%.
  Layer._call_arg_was_passed now has a shortcut for the common case.
diff: @@ -2308,15 +2308,17 @@ class Layer(module.Module, version_utils.LayerVersionSelector):
  return input_masks
  def _call_arg_was_passed(self, arg_name, args, kwargs, inputs_in_args=False):
  + # Performance optimization: do no work in most common case.
  + if not args and not kwargs:
  + return False
  +
  if arg_name in kwargs:
  return True
  call_fn_args = self._call_fn_args
  if not inputs_in_args:
  # Ignore `inputs` arg.
  call_fn_args = call_fn_args[1:]
  - if arg_name in dict(zip(call_fn_args, args)):
  - return True
  - return False
  + return arg_name in dict(zip(call_fn_args, args))
  def _get_call_arg_value(self, arg_name, args, kwargs, inputs_in_args=False):
  if arg_name in kwargs:
  