I need to access sforce.one in javascript inside a visualforce page that I'm including in a lightning component via iframe.

If I use the native "VisualForce" component then sforce.one is defined for me. But I'm short on vertical space and don't want to waste any on an extraneous title line and also I need to control the iframe height dynamically. So I created a simple component that includes the VF page in my own iframe, but sforce.one is NOT defined when I do it that way.