Use version of load() with option handling for window.loadAudio

[ben-denham]

I ran into the following error when attempting to use window.loadAudio() from a browser environment: Uncaught TypeError: options.fetch is not a function.

This seems to be because the window.loadAudio() function is load() in loads.js, which doesn't handle options like the function exported from browser.js.

This pull request resolves the issue by assigning the function exported from browser.js to window.loadAudio() instead.