Resolve "Some legacy pages apparently get build up/rendered twice"

Closes #841 (closed)

aleksis/core/frontend/components/LegacyBaseTemplate.vue

@@ -24,7 +24,6 @@
     :src="iFrameSrc"
     :height="iFrameHeight + 'px'"
     class="iframe-fullsize"
-    @load="load"
     ref="contentIFrame"
   ></iframe>
 </template>
@@ -132,6 +131,7 @@ export default {
     },
   },
   mounted() {
+    this.$refs.contentIFrame.addEventListener("load", (e) => {this.load()});
     this.iFrameSrc = "/django" + this.$route.path + this.queryString;
   },
   name: "LegacyBaseTemplate",