FF21: Why no scrollbars on SVG without explicit height?

Hi

Open this SVG file in Firefox 21.0:

https://sites.google.com/site/skissane/files/cleanblah.svg

The bottom of the image is cut off. And there is no vertical scroll bar.

Since my SVG lacks a height and width declared, my reading of the SVG spec is that both should default to 100% of the container, and thus all of my SVG should be displayed. If I explicitly specify a height, this problem goes away, but per the SVG spec I should not need one. (And, suppose the SVG is being generated programmatically - then calculating the correct height could be a lot of extra code.)

Alternatively, if Firefox is not going to scale it so it all displays, at least provide a vertical scrollbar so I can see it all by scrolling.

Also, the part cut off the bottom is missing even when I zoom out.

Question: Is this a bug in Firefox's SVG handling? Or am I just misunderstanding the SVG spec?

Thanks
Simon Kissane