Regarding coding style, gjs is moving in a direction that departs quite
significantly from the established style, in particular when indenting
multi-line array/object literals or method arguments:
Currently we are keeping those elements aligned, while the gjs rules now
expect them to use the regular 4-space indentation.
There are certainly good arguments that can be made for that move - it's
much less prone to leading to overly-long lines, and matches popluar JS
styles elsewhere. But switching coding style implies large diffs which
interfere with git-blame and friends, so in order to allow for a more
gradual change, add a separate set of "legacy" rules that match more
closely the style we would expect up to now.
It also disables the rules for quotes and template strings - the former
because we cannot match the current style to use double-quotes for
translatable strings and single-quotes otherwise, the latter because
template strings are still relatively new, so we haven't adopted them
yet.
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/609
