runtime(java): Improve the matching of contextual keywords

- Recognise a _record_ contextual keyword.
- Recognise _non-sealed_, _sealed_, and _permits_ contextual
  keywords.
- Admit _$_ to keyword characters.
- Group _abstract_, _final_, _default_, _(non-)sealed_
  (apart from _(non-)sealed_, the incompossibility of these
  modifiers calls for attention).
- Remove another _synchronized_ keyword redefinition.

I have also replaced a function with an expression.  Before
patch 8.1.0515, it should have been declared :function! to
work with repeatable script sourcing; there is less to worry
about with an expression.

References:
https://openjdk.org/jeps/395 (Records)
https://openjdk.org/jeps/409 (Sealed Classes)
https://docs.oracle.com/javase/specs/jls/se21/html/jls-3.html#jls-3.8

closes: #14403

Signed-off-by: Aliaksei Budavei <0x000c70@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

0 files changed, 0 insertions, 0 deletions