In the case of a lot running through from one street to another street, the front of such lot shall, for the purposes of this chapter, be considered that frontage upon which the majority of the buildings in the same block front; but in case there has been no clearly defined frontage established, the owner may, when applying for a building permit, specify on the permit application which lot line shall be considered the front line. The rear portion of such a lot shall, however, be treated as a front yard for the purposes of determining required setbacks and locations of permitted structures and uses.