message: Update gradient_descent.py
  removing grad.indices and replacing back grad
diff: @@ -56,7 +56,7 @@ class GradientDescentOptimizer(optimizer.Optimizer):
  return training_ops.apply_gradient_descent(
  var,
  math_ops.cast(self._learning_rate_tensor, var.dtype.base_dtype),
  - grad.indices,
  + grad,
  use_locking=self._use_locking).op
  def _resource_apply_dense(self, grad, handle):
  