WEB: support watch all of web_ui folder instead of only web_ui/lib

[zhangyuang]

Use case

When run felt build --watch in this project I find some problems with this code https://github.com/flutter/flutter/blob/master/engine/src/flutter/lib/web_ui/dev/build.dart#L96, flutter only supports watch web_ui/lib folder change when developing locally. I hope there can support watching all of the web_ui folders like the flutter_js folder because I want to re-execute the js bundle build by esbuild when files in flutter_js changed

Proposal

Change final FilePath libPath = FilePath.fromWebUi('lib'); to final FilePath libPath = FilePath.fromWebUi('.');

If it can be approved, I can submit a pull request

[yjbanov]

We probably don't want to watch all of web_ui to avoid recursion (felt itself lives inside web_ui), and churn (build artifacts are unstable). However, I think we can add a few more frequently edited directories (flutter_js, skwasm, maybe even test?).

[zhangyuang]

Sure, if you agree with it, i can try to implement watch more directories in local. Currently i debug with web_ui for support more platform like miniprogram.

[zhangyuang]

In my opinion, I want to implement these

• Support watch more directories, when files changed, the jobs of ninja will rebuild
• Avoid task conflict, when last build job not finished but next job trigger like esbuild + zip will cause the new job cannot be execute succeed
• Don't need to build the zip file of web artifact everytime in watch mode which will spend much time