title: Android WebView fails URL.createObjectUrl()
body: <p>We are devoloping a webapp which is embedded into a WebView-Container-App (basicly it's just an Activity with a fullscreen WebView calling <code>android.webkit.WebView.loadUrl(&lt;URL_TO_WEBAPP&gt;)</code>).
  At a certain point in the webapp's JavaScript code the function <code>URL.createObjectUrl</code> is called.
  Starting from API level 19 the webapp works as expected. But running the app in API level 18 and lower the following error occurs: <code>E/Web Console﹕ Uncaught ReferenceError: URL is not defined at &lt;URL_TO_JS_FILE&gt;</code>. I did an extensive search on the web but it seems like nobody ever had that problem before.</p>
  
  <p>We thought <code>window.URL</code> is a JavaScript standard function, so what could be the possible problem here?</p>