Suggestion: Make 'viewBox' a 'styling property'.

The 'viewBox' could be useful as a 'styling property'.

Also, a denizen of #svg suggested to me that 'viewBox' could take an 'auto'
value which "dynamically makes the viewbox be the 'decorated bounding box'
(e.g. geometry plus strokes, filters, etc.) of the content".

Cheers,
Beau Brueggemann