recover from unexpected brace at top-level

[sbfaulkner]

When minifying, esbuild will currently truncate output when it encounters an unexpected } at the top-level of the css.

Given CSS like...

.red {
  color: red;
}
}
.blue {
  color: blue;
}
.green {
  color: green;
}

This produces...

bin/esbuild --loader=css --minify <rgb.css
▲ [WARNING] Expected end of file but found "}"

    <stdin>:4:0:
      4 │ }
        ╵ ^

1 warning
.red{color:red}

This PR attempts to recover from the situation (more like the best-effort recovery seen in other minification processors and/or css parsers), instead producing the following...

bin/esbuild --loader=css --minify <rgb.css
▲ [WARNING] Unexpected "}"

    <stdin>:4:0:
      4 │ }
        ╵ ^

1 warning
.red{color:red}.blue{color:#00f}.green{color:green}

[sbfaulkner]

@evanw when you have time, is this the correct fix?

[evanw]

Yeah, looks good to me. Thanks!

[evanw]

Hmm actually when I run this in the browser, the result is different. Sorry for merging without checking first. In the browser, the red and green rules take effect but the blue rule doesn't. So esbuild should follow that behavior IMO. Still recover and continue but the rule starting with } is invalid. I'll change it to behave like that instead.