Update SlickGrid.d.ts

Added the overload for setData.

slickgrid/SlickGrid.d.ts

@@ -779,11 +779,18 @@ declare module Slick {
 
 		/**
 		* Sets a new source for databinding and removes all rendered rows. Note that this doesn't render the new rows - you can follow it with a call to render() to do that.
-		* @param newData New databinding source. This can either be a regular JavaScript array or a custom object exposing getItem(index) and getLength() functions.
+		* @param newData New databinding source using a regular JavaScript array..
 		* @param scrollToTop If true, the grid will reset the vertical scroll position to the top of the grid.
 		**/
 		public setData(newData: T[], scrollToTop: boolean): void;
 
+		/**
+		* Sets a new source for databinding and removes all rendered rows. Note that this doesn't render the new rows - you can follow it with a call to render() to do that.
+		* @param newData New databinding source using a custom object exposing getItem(index) and getLength() functions.
+		* @param scrollToTop If true, the grid will reset the vertical scroll position to the top of the grid.
+		**/
+		public setData(newData: { getItem: (index: number) => T; getLength: () => number; }, scrollToTop: boolean): void;
+
 		/**
 		* Returns the size of the databinding source.
 		* @return