Revert optional

d3/d3.d.ts

@@ -18,13 +18,13 @@ declare module D3 {
             *
             * @param selector Selection String to match
             */
-            (selector?: string): Selection;
+            (selector: string): Selection;
             /**
             * Selects the specified node
             *
             * @param element Node element to select
             */
-            (element?: EventTarget): Selection;
+            (element: EventTarget): Selection;
         };
 
         /**