Fix `onDownloadProgress` test commented out in test/browser.ts

[komura-c]

Hello, I noticed a test that was commented out in browser.ts and fixed it. When I uncommented it, I got a ReferenceError: __name is not undefined on playweight at the following location

const decodeUtf8 = (array: Uint8Array) => String.fromCodePoint(...array);

On playweight, it is executed as follows

const decodeUtf8 = __name((array) => String.fromCodePoint(...array), "decodeUtf8")

I found out that this was due to an optimization option keepNames in vite. refs: vite/pull/2376#issuecomment-805285480, esbuild/issues/2605#issue-1404600925

In this repository, it seems to be happening only within playweight. I don't think there is any need to make it a function except for readability, so I fixed it so that it doesn't create a function. Just to be sure, I tried it onDownloadProgress in a vite+react environment and the same thing did not happen, so it seems to be a good fix for testing only.

[sindresorhus]

Thanks :)