-e: Application.streamingAssetsPath is relative to the html index file loading the webgl player instead of the "UnityLoader.js" script, meaning you can't load streaming assets with the webgl player on any page not in the specific spot in the build folder that Unity puts the inex.html file in.

-repro:
--open attached project
--put the example folder on a server
--start the /index.html
--NOTICE that the streamingAssetPath relative the UnityLoader is wrong
--start the /Build/index-relative.html
--NOTICE that the streamingAssetPath relative the UnityLoader is correct

-proposed user solution:
"Example/Build/Build/RelativePathExample.js" shows how to build the streaming assets path relative to the "UnityLoader.js" file rather than the index.html file using "document.currentScript.src".