Fix a bug in SPLOM axes.

Array.reverse does not create a copy of the array, so we must slice first.

examples/splom/splom.js

@@ -12,7 +12,7 @@ d3.json("flowers.json", function(flower) {
         domain = [d3.min(flower.values, value), d3.max(flower.values, value)],
         range = [padding / 2, size - padding / 2];
     x[trait] = d3.scale.linear().domain(domain).range(range);
-    y[trait] = d3.scale.linear().domain(domain).range(range.reverse());
+    y[trait] = d3.scale.linear().domain(domain).range(range.slice().reverse());
   });
 
   // Axes.