修复有货币页面不滚动问题。code review by LZF

@@ -16,12 +16,16 @@ function ajaxCurrencyDetail(page) {
     });
 }
 
-$(window).scroll(function() {
-    if ($(window).scrollTop() + $(window).height() > $('body').height() - 1) {
+function scrollHandler() {
+    if ($(window).scrollTop() + $(window).height() > $('body').height() - 100) {
         page++;
         ajaxCurrencyDetail(page);
         return;
     }
+}
+
+$(window).scroll(function() {
+    window.requestAnimationFrame(scrollHandler);
 });
 
 ajaxCurrencyDetail(page);