this has nothing to do with javascript.
webview is not a replacement for your default browser.
if you look at the page in the developer tab of your desktop browser, you will see a number of errors. the biggest one has to do with a page that has been loaded using https loading other resources using http. there also appears to be some kind of login required. that one throws an error. while chrome may tend to gloss over such issues, webview (since it is not chrome and not meant to be used as a replacement for chrome) appears not to.
am attaching a screen cap from my desktop browser showing some of the errors.
if you can figure out what the deal is with the login, you might be able to get the thing to work, since that was the only statement which actually appears to throw an error.
unsolicited hint: if you know what you're doing, it might be possible to bypass that whole introduction page and go right to the music (i'm guessing that's what you're after). in many cases, the source of the media can be sitting in plain sight if you're comfortable combing through a webpage's source