update rc-steps v1.3.1 使用iframe来监控resize事件。未来不支持ie8后，再过渡到纯css实现。

package.json

@@ -52,7 +52,7 @@
     "rc-radio": "~2.0.0",
     "rc-select": "~4.9.0",
     "rc-slider": "~1.4.0",
-    "rc-steps": "~1.3.0",
+    "rc-steps": "~1.3.1",
     "rc-switch": "~1.2.0",
     "rc-table": "~3.2.0",
     "rc-tabs": "~5.3.2",

style/components/steps.less

@@ -21,11 +21,22 @@
   -moz-transition: @transition;
 }
 
+.@{steps-prefix-cls}-resize-frame {
+  height: 0;
+  background-color: transparent;
+  margin: 0;
+  padding: 0;
+  overflow: hidden;
+  border-width: 0;
+  position: absolute;
+  width: 100%;
+}
+
 .@{steps-prefix-cls} {
   font-size: 0;
   width: 100%;
   line-height: 1.5;
-
+  position: relative;
   .@{steps-prefix-cls}-item {
     position: relative;
     display: inline-block;