Bug 834414 - Remove unnecessary getInstance call that was leaking an App instance. r=wesj

mobile/android/base/GeckoAppShell.java

@@ -533,8 +533,6 @@ public class GeckoAppShell
     }
 
     public static void runGecko(String apkPath, String args, String url, String type) {
-        WebAppAllocator.getInstance();
-
         Looper.prepare();
         sGeckoHandler = new Handler();