This PR was merged into the 1.4-dev branch.

Discussion
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Fix the support of legacy scssphp formatters

Scssphp 0.5 removed the deprecated classes. But as there was no warning, people might not be aware that they were using a deprecated class.
This keeps support for the deprecated formatters in Assetic by matching them to their replacement, and warns the user about it.

Commits
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b422ec4 Update the scssphp tests to be less strict about formatting
d6641a5 Fix the support of legacy scssphp formatters