Fix tab muting

Author: pfrazee

app/bg/ui/tabs/manager.js

@@ -235,10 +235,8 @@ class Tab extends EventEmitter {
   }
 
   toggleMuted () {
-    let isMuted = this.panes.reduce((v, pane) => v || pane.isAudioMuted, false)
-    for (let pane of this.panes) {
-      pane.setAudioMuted(!isMuted)
-    }
+    this.activePane.toggleMuted()
+    this.emitTabUpdateState(this.activePane)
   }
 
   // panes

app/bg/ui/tabs/pane.js

@@ -425,7 +425,6 @@ export class Pane extends EventEmitter {
 
   toggleMuted () {
     this.webContents.setAudioMuted(!this.isAudioMuted)
-    this.emitUpdateState()
   }
 
   async captureScreenshot () {

app/fg/shell-window/tabs.js

@@ -491,7 +491,7 @@ ${spinnerCSS}
 .fa-volume-up,
 .fa-volume-mute {
   position: absolute;
-  top: 8px;
+  top: 6px;
   right: 10px;
   font-size: 12px;
   color: rgba(0,0,0,.6);