fix(compiler-core): improve member expression check

[gucovip]

close #8939

[Justineo]

According to the spec, the accurate regexp for identifiers (disregarding unicode escape sequences) should be

/^[$_\p{IDS}][$\p{IDC}\u200c\u200d]*/u

But this may have browser compatibility issues so we may need a simplified version. Where does this \xA0-\uFFFF come from in your change?

[gucovip]

According to the spec, the accurate regexp for identifiers (disregarding unicode escape sequences) should be

/^[$_\p{IDS}][$\p{IDC}\u200c\u200d]*/u

But this may have browser compatibility issues so we may need a simplified version. Where does this \xA0-\uFFFF come from in your change?

reference code const validFirstIdentCharRE = /[A-Za-z_$\xA0-\uFFFF]/ (line: 74)

[skirtles-code]

Would it be worth adding some tests for this? I can easily imagine somebody trying to tweak that RegExp in future and accidentally breaking support for Chinese characters.

[skirtles-code]

Seems similar to #6765.