macOS: Simplify validAttributesForMarkedText

We don't need to condition this on IM enablement. The attributes are
only used if we are actually marking text, which only happens for IM
enabled views.

Pick-to: 6.2
Change-Id: I47377cf53cf2bf44a1d9513d317f82c73f083fa3
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

src/plugins/platforms/cocoa/qnsview_complextext.mm

@@ -183,16 +183,7 @@
 
 - (NSArray<NSString *> *)validAttributesForMarkedText
 {
-    if (!m_platformWindow)
-        return nil;
-
-    if (m_platformWindow->window() != QGuiApplication::focusWindow())
-        return nil;
-
-    if (queryInputMethod(m_platformWindow->window()->focusObject()))
-        return @[NSUnderlineColorAttributeName, NSUnderlineStyleAttributeName];
-    else
-        return nil;
+    return @[NSUnderlineColorAttributeName, NSUnderlineStyleAttributeName];
 }
 
 - (BOOL)hasMarkedText