Remove redeclarations

Created by: shemgp

Extension won't load on GNOME 2.24 on Ubuntu 17.04 because of redeclaration of variables.

Here's a sample output from journalctl /usr/bin/gnome-shell:

JS ERROR: Exception in callback for signal: extension-found: TypeError: redeclaration of let themeNode
@/home/shemgp/.local/share/gnome-shell/extensions/gnomeGlobalAppMenu@lestcape/extensionManager.js:30:7
@/home/shemgp/.local/share/gnome-shell/extensions/gnomeGlobalAppMenu@lestcape/extension.js:8:7
initExtension@resource:///org/gnome/shell/ui/extensionSystem.js:221:5
loadExtension@resource:///org/gnome/shell/ui/extensionSystem.js:168:18
_loadExtensions/<@resource:///org/gnome/shell/ui/extensionSystem.js:304:9
_emit@resource:///org/gnome/gjs/modules/signals.js:126:27
ExtensionFinder<._loadExtension@resource:///org/gnome/shell/misc/extensionUtils.js:184:9
wrapper@resource:///org/gnome/gjs/modules/lang.js:178:22
bind/<@resource:///org/gnome/gjs/modules/lang.js:95:16
collectFromDatadirs@resource:///org/gnome/shell/misc/fileUtils.js:27:1
ExtensionFinder<.scanExtensions@resource:///org/gnome/shell/misc/extensionUtils.js:189:9
wrapper@resource:///org/gnome/gjs/modules/lang.js:178:22
_loadExtensions@resource:///org/gnome/shell/ui/extensionSystem.js:306:5
enableAllExtensions@resource:///org/gnome/shell/ui/extensionSystem.js:314:9
_sessionUpdated@resource:///org/gnome/shell/ui/extensionSystem.js:345:9
init@resource:///org/gnome/shell/ui/extensionSystem.js:353:5
_initializeUI@resource:///org/gnome/shell/ui/main.js:219:5
start@resource:///org/gnome/shell/ui/main.js:127:5
@<main>:1:31

With this PR it will load but I can't still see the global menu.