[Dependency] Fix compatibility issue with less >= 3.5 due to math changes

[sciyoshi]

A follow-up to #6447, there's a new change in less 3.5 for how calculations are handled. This PR avoids the current interpolation that's happening and simply uses calc(). The compiled CSS will be a bit different but should work the same way.

Closes Semantic-Org/Semantic-UI-LESS#30, Semantic-Org/Semantic-UI-LESS#46, #6470.

[sciyoshi]

cc @jlukic @levithomason

[RussBrown00]

For whats it's worth, this fixes the bug - :LGTM:

[daniel-cottone]

@jlukic @levithomason Can we get a review on this PR?

[ColinFrick]

Applying this patch will break with the current build system (gulp-less@3.5.0):
@tabularFluidWidth: calc(100% + (@tabularFluidOffset * 2));
will output
calc(102%)

[corydeppen]

Is there anything preventing the fix introduced in fomantic/Fomantic-UI#97 from being merged here?

[jlukic]

I'm going to look into adding this as a patch. Got lost in the shuffle.

Feel free to email me at jack@semantic-ui.com if there are breaking changes like this, github is difficult for me to parse notifications.

[courdek]

Any idea on when this patch may find its way into the npm packages?

[jlukic]

I've validated this and merged it into next in 5e8dcde

I've also added some additional calc swaps here 4b4df6c

I've updated our build pipeline to enforce a minimum build of gulp-less that supports the new syntax. As this will not work in older versions of less and will cause breaking changes. aae225a

I'll make a note of the requirement for those using older versions of LESS with the less only package to update in the release notes.

[brendon]

Does this mean that building Semantic-UI-Rails-LESS against https://github.com/metaskills/less-rails which uses https://github.com/cowboyd/less.rb which seems stuck at Less 1.7.0 will now fail?

Looks like a perfect storm of abandoned dependencies! :D