+ ruby27.y: fix array pattern with tail source map

[palkan]

This change takes trailing comman into account for array_pattern_with_tail expression location:

# before
in foo,
   ~~~ expression

# after
in foo,
   ~~~~ expression

Currently, we lose comma location information, which makes it hard for rewriters to deal with this case.

[palkan]

@iliabylich Another source map related question I would like to ask about first: what is the reason for the existing const_pattern behavior with expression to not including the const itself?

in A[0,1]
    ~~~~~ expression (in_pattern.const_pattern)
   ~ expression (in_pattern.const_pattern.const)

Do we already have such examples when a child node's expression is located outside of the parent node?

[iliabylich]

Do we already have such examples when a child node's expression is located outside of the parent node?

No, that's a bug. Could you send a PR to fix it please? If not I'll find some time next week.

[iliabylich]

LGTM

[palkan]

Could you send a PR to fix it please?

Sure.