Fixed a bug with scatterCharts not respecting changes to scales

Setting a scale/range/domain (say, an ordinal scale) on the scatterChart after creating it would set the xScale and yScale properties of scatter, but x and y in the chart() function of scatterChart are never updated with the latest scales that had been set on scatter.  Instead x and y retain the initial values given to them upon creation (linear scales typically).  I moved the code around so the scales behave more like that of line charts, and are pulled from scatter.xScale() / scatter.yScale() before drawing.