Add Selection.classed(object)

.classed() allows an object map as input, similar to .attr() and .style().

d3/d3.d.ts

@@ -719,6 +719,7 @@ declare module D3 {
             (name: string): string;
             (name: string, value: any): Selection;
             (name: string, valueFunction: (data: any, index: number) => any): Selection;
+            (classValueMap: Object): Selection;
         };
 
         style: {