codemirror5: Failing cases in JSX mode

Following up on: https://github.com/codemirror/CodeMirror/pull/3742

Three from the jsx/index.html page:

1. Boolean attributes are not recognized properly (note the red self-closing />)
2. Block comments styled incorrectly (should be the brown comment color)
3. Line comments are not recognized properly (note the red self-closing />)

Two other things I’ve found:

4 . Elements should be allowed as attributes

5 . Indentation in JS expressions should be relative to the indentation level of JSX elements. I believe currently they get indented to prior JS indentation level. (this issue is highest priority, if I had to choose)

Current behavior gif here:

Correct position here:

Another example of current behavior (not followed by } char):

Correct position here:

@parisk @petetnt