Fix issue with webviews.
Fix issue with webviews.

We were instantiating a WKWebView on a background thread and even though
we weren't doing anything with it, it borked everything.

Weirdly this was impacting both WKWebView and UIWebView.

edx/edx-app-ios,edx/edx-app-ios,Ben21hao/edx-app-ios-new,edx/edx-app-ios,edx/edx-app-ios,Ben21hao/edx-app-ios-enterprise-new,Ben21hao/edx-app-ios-enterprise-new,appsembler/edx-app-ios,proversity-org/edx-app-ios,edx/edx-app-ios,proversity-org/edx-app-ios,proversity-org/edx-app-ios,Ben21hao/edx-app-ios-enterprise-new,Ben21hao/edx-app-ios-new,edx/edx-app-ios,appsembler/edx-app-ios,proversity-org/edx-app-ios,Ben21hao/edx-app-ios-new,edx/edx-app-ios,Ben21hao/edx-app-ios-enterprise-new,appsembler/edx-app-ios,proversity-org/edx-app-ios,Ben21hao/edx-app-ios-enterprise-new,Ben21hao/edx-app-ios-new,appsembler/edx-app-ios,proversity-org/edx-app-ios,appsembler/edx-app-ios,Ben21hao/edx-app-ios-new