fix scroller, soundjs and youtube definitions

scroller/easyscroller.d.ts

@@ -6,7 +6,7 @@
 
 /// <reference path="scroller.d.ts"/>
 
-class EasyScroller  {
+declare class EasyScroller  {
     constructor (content: any, options: ScrollerOptions);
 
     render(): void;

scroller/scroller-tests.ts

@@ -41,7 +41,7 @@ function test_canvas() {
 function test_domlist() {
     var container = document.getElementById("container");
     var content = document.getElementById("content");
-    var refreshElem = <HTMLCanvasElement>content.getElementsByTagName("div")[0];
+    var refreshElem = content.getElementsByTagName("div")[0];
     var scroller = new Scroller(render, {
         scrollingX: false
     });

scroller/scroller.d.ts

@@ -28,7 +28,7 @@ interface ScrollValuesWithZoom extends ScrollValues {
     zoom: number;
 }
 
-class Scroller {
+declare class Scroller {
     constructor (callback: (left: number, top: number, zoom: number) => void , options: ScrollerOptions);
 
     setDimensions(clientWidth: number, clientHeight: number, contentWidth: number, contentHeight: number): void;