Issue #1107: Bubble chart only expand canvas
Issue #1107: Bubble chart only expand canvas

In the bubble chart, only expand canvas when the "Follow bubbles with zoom
option" is selected. Bubble chart will only zoom out when following bubbles and
never zoom in.

sergey-filipenko/vizabi,Gapminder/vizabi,sergey-filipenko/vizabi,dab2000/vizabi,vizabi/vizabi,vizabi/vizabi,Gapminder/vizabi,buchslava/vizabi,sergey-filipenko/vizabi,Gapminder/vizabi,dab2000/vizabi,buchslava/vizabi,buchslava/vizabi,dab2000/vizabi