fix some tree style

components/tree/demo/dynamic.md

@@ -80,7 +80,7 @@ const Demo = React.createClass({
         getNewTreeData(treeData, treeNode.props.eventKey, generateTreeNodes(treeNode), 2);
         this.setState({ treeData });
         resolve();
-      }, 500);
+      }, 1000);
     });
   },
   render() {

components/tree/style/index.less

@@ -91,9 +91,8 @@
           content: '\e6a1';
           display: inline-block;
           font-family: 'anticon';
-          font-weight: bold;
           animation: loadingCircle 1s infinite linear;
-          margin-top: 8px;
+          color: @primary-color;
         }
       }
       &.@{tree-prefix-cls}-switcher {

components/tree/style/mixin.less

@@ -9,7 +9,7 @@
     font-family: 'anticon';
     font-weight: bold;
     position: absolute;
-    top: 0;
+    top: 1px;
     right: 4px;
     color: #666;
     transition: transform .3s ease;