Bug 1398980 - Remove warning about stylo not supporting document state changes. r=me

It's spammy and we already have a bug on file.

MozReview-Commit-ID: DB7KGuj0V3I

layout/base/PresShell.cpp

@@ -4293,9 +4293,6 @@ PresShell::DocumentStatesChanged(nsIDocument* aDocument,
     // XXXheycam ServoStyleSets don't support document state selectors,
     // but these are only used in chrome documents, which we are not
     // aiming to support yet.
-    NS_WARNING("stylo: ServoStyleSets cannot respond to document state "
-               "changes yet (only matters for chrome documents). See bug 1290285.");
-
   } else if (mDidInitialize &&
              geckoSet->HasDocumentStateDependentStyle(mDocument->GetRootElement(),
                                                       aStateMask)) {