HackStudio: Abstract over syntax highlighter

Author: https://github.com/oriko1010
Commit: 137d68a2ae
Pull-request: https://github.com/SerenityOS/serenity/pull/1429
Reviewed-by: https://github.com/awesomekling

Libraries/LibGUI/TextEditor.cpp

@@ -1497,10 +1497,7 @@ void TextEditor::flush_pending_change_notification_if_needed()
 
 const SyntaxHighlighter* TextEditor::syntax_highlighter() const
 {
-    if (m_highlighter)
-        return m_highlighter.ptr();
-    else
-        return nullptr;
+    return m_highlighter.ptr();
 }
 
 void TextEditor::set_syntax_highlighter(OwnPtr<SyntaxHighlighter> highlighter)