operator.cc: remove check for empty repeated argument (to allow empty shapes and other use cases)
operator.cc: remove check for empty repeated argument (to allow empty
shapes and other use cases)

pietern/caffe2,bwasti/caffe2,Yangqing/caffe2,pietern/caffe2,xzturn/caffe2,Yangqing/caffe2,sf-wind/caffe2,caffe2/caffe2,davinwang/caffe2,Yangqing/caffe2,sf-wind/caffe2,xzturn/caffe2,bwasti/caffe2,davinwang/caffe2,davinwang/caffe2,sf-wind/caffe2,xzturn/caffe2,bwasti/caffe2,bwasti/caffe2,pietern/caffe2,pietern/caffe2,sf-wind/caffe2,davinwang/caffe2,Yangqing/caffe2,Yangqing/caffe2,pietern/caffe2,xzturn/caffe2,bwasti/caffe2,xzturn/caffe2,davinwang/caffe2,sf-wind/caffe2