Fix event handler deregistration in TopBar

Even if their code is identical two arrow functions are different
instances, so the original one was not properly deregistered.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>

src/components/TopBar/TopBar.vue

@@ -359,9 +359,7 @@ export default {
 		document.addEventListener('MSFullscreenChange', this.fullScreenChanged, false)
 		document.addEventListener('webkitfullscreenchange', this.fullScreenChanged, false)
 		// Add call layout hint listener
-		EventBus.$on('toggleLayoutHint', (display) => {
-			this.showLayoutHint = display
-		})
+		EventBus.$on('toggleLayoutHint', this.handleToggleLayoutHint)
 	},
 
 	beforeDestroy() {
@@ -370,9 +368,7 @@ export default {
 		document.removeEventListener('MSFullscreenChange', this.fullScreenChanged, false)
 		document.removeEventListener('webkitfullscreenchange', this.fullScreenChanged, false)
 		// Remove call layout hint listener
-		EventBus.$off('toggleLayoutHint', (display) => {
-			this.showLayoutHint = display
-		})
+		EventBus.$off('toggleLayoutHint', this.handleToggleLayoutHint)
 	},
 
 	methods: {
@@ -489,6 +485,9 @@ export default {
 			this.$store.dispatch('isRenamingConversation', true)
 			this.$store.dispatch('showSidebar')
 		},
+		handleToggleLayoutHint(display) {
+			this.showLayoutHint = display
+		},
 		forceMuteOthers() {
 			callParticipantCollection.callParticipantModels.forEach(callParticipantModel => {
 				callParticipantModel.forceMute()