ImgView JS bug fixed

From the Android 4.2 documentation:
Caution: If you've set your targetSdkVersion to 17 or higher, you must
add the @JavascriptInterface annotation to any method that you want
available your web page code (the method must also be public). If you
do not provide the annotation, then the method will not accessible by
your web page when running on Android 4.2 or higher.