[Issue 18879] !is doesn't highlight correctly

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18879

--- Comment #9 from Rainer Schuetze <r.sagitario at gmx.de> ---
Keywords are blue by default, operators have the default color depending on the
theme, so usually black or white.

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