Theme compiler bug - filter: invert

[vaadin-bot]

Originally by g.mwralhs

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The following style in the SCSS file

img.invertContent{
background: inherit;
filter: invert(100%) !important;
}

will compile as

.mystyle img.invertContent {
background: inherit;
}

It seams there is a bug with the invert filter, it is not recognized since other filters are accepted. Without including another CSS style inside the class with the invert filter, it won't even appear at all.

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Imported from https://dev.vaadin.com/ issue #18982