feat: Collapse兼容ie8和Safari

closes #138, #161

Conflicts:
	style/components/collapse.less

style/components/collapse.less

@@ -23,20 +23,28 @@
     > .@{collapse-prefix-cls}-header {
       height: 38px;
       line-height: 38px;
-      padding-left: 16px;
+      padding-left: 32px;
       color: #666;
       cursor: pointer;
-      &:before {
-        font-family: "anticon" !important;
+      position: relative;
+
+      .arrow {
+        #arrow > .close();
+        .iconfont-mixin();
+        position: absolute;
         color: #666;
         display: inline-block;
         margin-right: 8px;
         content: "\e60f";
-        #arrow > .close();
         vertical-align: middle;
         transition: transform 0.24s ease;
-        position: relative;
         top: -1px;
+        left: 16px;
+        top: ~"16px \9";
+        left: ~"0 \9";
+        &:before {
+          content:"\e60f";
+        }
       }
     }
   }
@@ -55,9 +63,8 @@
   }
 
   &-collapsing {
-    transition-duration: .3s;
-    transition-timing-function: cubic-bezier(0.215, 0.61, 0.355, 1);
-    transition-property: height;
+    transition-duration: .24s;
+    transition-timing-function: @ease-out-circ;
   }
 
   &-item:last-child {
@@ -73,7 +80,9 @@
   & > &-item-active {
     > .@{collapse-prefix-cls}-header {
 
-      &:before {
+      .arrow {
+        top: -1px;
+        left: 16px;
         #arrow > .open();
       }
     }