cleanupClassNames #2162
Description
Is your plugin request related to a problem? Please describe.
prefixIds also prefixes classes with the prefixClassNames parameter set to true. This is good. Issue is that if svgo is called to a file for a second time, while all the Ids can be cleaned up first by cleanupIds, and then their values be reset, the classnames won't, causing terrible class attributes like: class="uswv-uswv-uswv-UnoptimicedTransforms" (try guessing what the prefix is here)
Describe what the plugin should do
It should literally be cleanupIds but for classes.