Add non-standard cross-browser fields support

[cezaraugusto]

Address #122

[joeframbach]

This won't recurse in child arrays, if it matters.

{
  "foo": [
    {} // <--- won't touch this
  ]
}

[joeframbach]

I may suggest

  private reviver (this: any, key: string, value: any) {
    if (
      key.startsWith(`${this.browser}:`) ||
      (key.startsWith('chromium:') &&
        this.chromiumBasedBrowsers.includes(this.browser))
    ) {
      this[key.substring(key.indexOf(':')+1)] = value;
      return
    }

    if (key.includes(':')) {
      return
    }

    return value
  }

  apply(compiler: Compiler) {
    compiler.hooks.emit.tapAsync(
      'HandleBrowserSpecificFields',
      (compilation, done) => {
        if (compilation.errors.length > 0) return

        const manifestSource = compilation
          .getAsset('manifest.json')
          ?.source.source()
        const manifest = JSON.parse((manifestSource || '{}').toString(), this.reviver)
        const patchedSource = JSON.stringify(manifest, null, 2)
        const rawSource = new sources.RawSource(patchedSource)

        compilation.updateAsset('manifest.json', rawSource)

        done()
      }
    )
  }

[cezaraugusto]

hi @joeframbach, thanks for the tip!

Could you push a pull-request with the changes? I'll happily review it. I've been wanting this feature for a while but got to fix a few bugs first

[cezaraugusto]

suppressed by #128