Make the '-moz-windows-accent-color-applies' media query live to Windows 10 settings changes.

layout/base/nsPresContext.cpp

@@ -1733,6 +1733,9 @@ nsPresContext::SysColorChangedInternal()
     sLookAndFeelChanged = false;
   }
 
+  // Invalidate cached '-moz-windows-accent-color-applies' media query:
+  nsCSSRuleProcessor::FreeSystemMetrics();
+
   // Reset default background and foreground colors for the document since
   // they may be using system colors
   GetDocumentColorPreferences();