Improve support for #region in javascript code

[fab1o]

Support for #region is buggy. It only works for the first region but the second region cannot be folded.

• VSCode Version: 1.23.0-insider
• OS Version: Both Windows 10 and macOS High Sierra

Steps to Reproduce:

1. Create a new javascript file
2. Copy and paste the code below

class Testing {
    // #region prop
    get prop() {
        return 0;
    }
    set prop(p) {}
    // #endregion

    // #region prop2
    get prop2() {
        return 0;
    }
    set prop2(p) {}
    // #endregion
}

Result:

Does this issue occur when all extensions are disabled?: Yes

[vscodebot]

(Experimental duplicate detection)
Thanks for submitting this issue. Please also check if it is already covered by an existing one, like:

• Fold all regions not working for VSCode (#46776)
• Add region commenting feature/ Collapse code by region (#26901)
• Collapse/expand regions does not work (#47308)
• #region comments not working right since March update (#47401)

[mjbvz]

Same root cause as microsoft/TypeScript#23270