fix: Unsupported URL issue on Ionic WKWebView

Author: liammazy

lib/imgcache.js

@@ -179,6 +179,7 @@ LOG_LEVEL_ERROR = 3;
   Helpers.ionicNormalizer =  window.Ionic &&
       ((window.Ionic.WebView && window.Ionic.WebView.convertFileSrc) || window.Ionic.normalizeURL);
 
+  // check if ionic webview convertfilesrc function exist
   Helpers.isIonicNormalizerFunctionExist = function() {
     return (typeof Helpers.ionicNormalizer === 'function');
   };