Fix dragzoomx quicktest to not zoom in if start and end x values are the same.
Fix dragzoomx quicktest to not zoom in if start and end x values are the same.

Such as when there's a click without a drag.

onaio/plottable,NextTuesday/plottable,iobeam/plottable,alyssaq/plottable,RobertoMalatesta/plottable,palantir/plottable,NextTuesday/plottable,jacqt/plottable,softwords/plottable,iobeam/plottable,softwords/plottable,RobertoMalatesta/plottable,palantir/plottable,gdseller/plottable,onaio/plottable,RobertoMalatesta/plottable,jacqt/plottable,palantir/plottable,alyssaq/plottable,gdseller/plottable,gdseller/plottable,NextTuesday/plottable,danmane/plottable,palantir/plottable,jacqt/plottable,danmane/plottable,alyssaq/plottable,iobeam/plottable,danmane/plottable,softwords/plottable,onaio/plottable