use Application cache resources inside Iframe.
<script src="lib/WMAppCacheProxy.js"></script>
<script>
WMAppCacheProxy.createProxyURL(url, mimeType, function(err, blobURL){
console.log(blobURL);
});
</script>
importScripts("lib/WMAppCacheProxy.js");
WMAppCacheProxy.createProxyURL(url, mimeType, function(err, blobURL){
console.log(blobURL);
});