Fixup marker update in Scatter plot
Fixup marker update in Scatter plot

SylvainCorlay/bqplot,SylvainCorlay/bqplot,ChakriCherukuri/bqplot,bloomberg/bqplot,dmadeka/bqplot,ChakriCherukuri/bqplot,ChakriCherukuri/bqplot,bloomberg/bqplot,bloomberg/bqplot,dmadeka/bqplot,SylvainCorlay/bqplot