fix for vuejs/core#5417

Author: limenet

src/components/map/GlMap.js

@@ -109,14 +109,14 @@ export default {
   },
 
   render() {
-    if (!this.$_containerVNode) {
-      this.$_containerVNode = h("div", {
+    if (!this.$data.$_containerVNode) {
+      this.$data.$_containerVNode = h("div", {
         id: this.container,
         ref: "container"
       });
     }
     return h("div", { class: "mgl-map-wrapper" }, [
-      this.$_containerVNode,
+      this.$data.$_containerVNode,
       this.initialized ? this.$slots.default() : null
     ]);
   },