add support to open devtools for webview content

app/lib/menu.js

@@ -87,7 +87,7 @@ module.exports = function (window) {
           label: 'Toggle DevTools',
           accelerator: 'Alt+Command+I',
           click: function() { 
-            window.toggleDevTools()
+            window.rpc.contextualToggleDevTools()
           }
         },
       ]

app/lib/muxrpc-ipc.js

@@ -5,7 +5,8 @@ var pushable   = require('pull-pushable')
 var Api        = require('scuttlebot/lib/api')
 
 var clientApi = {
-  navigate: 'async'
+  navigate: 'async',
+  contextualToggleDevTools: 'async'
 }
 
 module.exports = function (window, sbot, params) {