migrate scroll utils to src

packages/waterfall/src/directive.js

@@ -1,4 +1,4 @@
-import Utils from './utils.js';
+import Utils from 'src/utils/scroll.js';
 
 const CONTEXT = '@@Waterfall';
 const OFFSET = 300;

packages/waterfall/src/utils.js

@@ -1,75 +0,0 @@
-export default {
-  debounce(func, wait, immediate) {
-    var timeout, args, context, timestamp, result;
-    return function() {
-      context = this;
-      args = arguments;
-      timestamp = new Date();
-      var later = function() {
-        var last = (new Date()) - timestamp;
-        if (last < wait) {
-          timeout = setTimeout(later, wait - last);
-        } else {
-          timeout = null;
-          result = func.apply(context, args);
-        }
-      };
-      if (!timeout) {
-        timeout = setTimeout(later, wait);
-      }
-      return result;
-    };
-  },
-
-  // 找到最近的触发滚动事件的元素
-  getScrollEventTarget(element) {
-    var currentNode = element;
-    // bugfix, see http://w3help.org/zh-cn/causes/SD9013 and http://stackoverflow.com/questions/17016740/onscroll-function-is-not-working-for-chrome
-    while (currentNode && currentNode.tagName !== 'HTML' && currentNode.tagName !== 'BODY' && currentNode.nodeType === 1) {
-      var overflowY = this.getComputedStyle(currentNode).overflowY;
-      if (overflowY === 'scroll' || overflowY === 'auto') {
-        return currentNode;
-      }
-      currentNode = currentNode.parentNode;
-    }
-    return window;
-  },
-
-  // 判断元素是否被加入到页面节点内
-  isAttached(element) {
-    var currentNode = element.parentNode;
-    while (currentNode) {
-      if (currentNode.tagName === 'HTML') {
-        return true;
-      }
-      if (currentNode.nodeType === 11) {
-        return false;
-      }
-      currentNode = currentNode.parentNode;
-    }
-    return false;
-  },
-
-  // 获取滚动高度
-  getScrollTop(element) {
-    return 'scrollTop' in element ? element.scrollTop : element.pageYOffset;
-  },
-
-  // 获取元素距离顶部高度
-  getElementTop(element) {
-    if (element === window) {
-      return this.getScrollTop(window);
-    }
-    return element.getBoundingClientRect().top + this.getScrollTop(window);
-  },
-
-  getVisibleHeight(element) {
-    if (element === window) {
-      return element.innerHeight;
-    }
-
-    return element.getBoundingClientRect().height;
-  },
-
-  getComputedStyle: document.defaultView.getComputedStyle.bind(document.defaultView)
-};