Ignore error when attempting to remove IAB event listeners

www/assets/js/platform.js

@@ -184,11 +184,17 @@ function initCordova() {
             }
             cordovaInAppBrowserRef = cordova.InAppBrowser.open(url, "_blank", options);
             if (typeof onclose == "function") {
-                cordovaInAppBrowserRef.removeEventListener("exit");
+                try {
+                    cordovaInAppBrowserRef.removeEventListener("exit");
+                } catch (ex) {
+                }
                 cordovaInAppBrowserRef.addEventListener("exit", onclose);
             }
             if (typeof onmessage == "function") {
-                cordovaInAppBrowserRef.removeEventListener("message");
+                try {
+                    cordovaInAppBrowserRef.removeEventListener("message");
+                } catch (ex) {
+                }
                 cordovaInAppBrowserRef.addEventListener("message", onmessage);
             }
         }