Remove unused qTopLevelDomain()

The last (and only) user was removed in 4f076db3d2.

Change-Id: I59b155017bfd00bbcbfe72dc0e535c92c0384dad
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/network/kernel/qtldurl.cpp

@@ -87,29 +87,6 @@ static bool containsTLDEntry(QStringView entry, TLDMatchType match)
     return false;
 }
 
-/*!
-    \internal
-
-    Return the top-level-domain per Qt's copy of the Mozilla public suffix list of
-    \a domain.
-*/
-
-Q_NETWORK_EXPORT QString qTopLevelDomain(const QString &domain)
-{
-    const QString domainLower = domain.toLower();
-    QVector<QStringRef> sections = domainLower.splitRef(QLatin1Char('.'), Qt::SkipEmptyParts);
-    if (sections.isEmpty())
-        return QString();
-
-    QString level, tld;
-    for (int j = sections.count() - 1; j >= 0; --j) {
-        level.prepend(QLatin1Char('.') + sections.at(j));
-        if (qIsEffectiveTLD(level.rightRef(level.size() - 1)))
-            tld = level;
-    }
-    return tld;
-}
-
 /*!
     \internal
 

src/network/kernel/qtldurl_p.h

@@ -59,7 +59,6 @@ QT_REQUIRE_CONFIG(topleveldomain);
 
 QT_BEGIN_NAMESPACE
 
-Q_NETWORK_EXPORT QString qTopLevelDomain(const QString &domain);
 Q_NETWORK_EXPORT bool qIsEffectiveTLD(QStringView domain);
 inline bool qIsEffectiveTLD(const QString &domain)
 {