DevTools: Get rid of WebInspector.panels

Source/devtools/front_end/extensions/ExtensionServer.js

Index: Source/devtools/front_end/extensions/ExtensionServer.js
diff --git a/Source/devtools/front_end/extensions/ExtensionServer.js b/Source/devtools/front_end/extensions/ExtensionServer.js
index 539950d516b99e087854a116ac284af58f15f7ff..d8c62153555b00d93c13eddadc7877af8b2ef5f3 100644
--- a/Source/devtools/front_end/extensions/ExtensionServer.js
+++ b/Source/devtools/front_end/extensions/ExtensionServer.js
@@ -220,7 +220,7 @@ WebInspector.ExtensionServer.prototype = {
         var id = message.id;
         // The ids are generated on the client API side and must be unique, so the check below
         // shouldn't be hit unless someone is bypassing the API.
-        if (id in this._clientObjects || id in WebInspector.panels)
+        if (id in this._clientObjects || WebInspector.inspectorView.hasPanel(id))
             return this._status.E_EXISTS(id);
 
         var page = this._expandResourcePath(port._extensionOrigin, message.page);