prerender offscreen pages

services/web/public/coffee/ide/pdfng/directives/pdfViewer.coffee

@@ -258,7 +258,7 @@ define [
 
 				renderVisiblePages = () ->
 					pages = getVisiblePages()
-					# pages = getExtraPages visiblePages
+					pages = getExtraPages visiblePages
 					scope.document.renderPages(pages)
 
 				getVisiblePages = () ->