Missing source maps in `proto-loader` npm releases

[chm-diederichs]

Hi I'm running into a DevTools error regarding missing source maps in the proto-loader package.

DevTools expects the following source maps: build/src/index.js.map & build/src/util.js.map to be present, however .map files are not included in the release.

Would it be possible to do either of the following:

1. Include .map files in the npm release

2. set compilerOptions.sourceMap = false so that // # sourceMappingURLs are omitted and DevTools does not load the missing map files

Thanks!

[chm-diederichs]

For convenience, I opened a PR for disabling source maps by default.

Let me know f you are interested or have any feedback.