don't stack up "no highlighting information" info bars

don't try to add another bar one if there is one already

Task-number: QTCREATORBUG-4951
Change-Id: Ia7282a5ee96d3b6b08b3f66c3bc162b1c4a5a015
Reviewed-on: http://codereview.qt.nokia.com/32
Reviewed-by: Leandro T. C. Melo <leandro.melo@nokia.com>

src/plugins/texteditor/basetextdocument.cpp

@@ -228,6 +228,7 @@ public:
 
     bool m_fileIsReadOnly;
     bool m_hasDecodingError;
+    bool m_hasHighlightWarning;
     QByteArray m_decodingErrorSample;
     static const int kChunkSize;
 
@@ -245,6 +246,7 @@ BaseTextDocumentPrivate::BaseTextDocumentPrivate(BaseTextDocument *q) :
     m_fileHasUtf8Bom(false),
     m_fileIsReadOnly(false),
     m_hasDecodingError(false),
+    m_hasHighlightWarning(false),
     m_autoSaveRevision(-1)
 {
 }
@@ -716,6 +718,16 @@ void BaseTextDocument::documentClosing()
     }
 }
 
+bool BaseTextDocument::hasHighlightWarning() const
+{
+    return d->m_hasHighlightWarning;
+}
+
+void BaseTextDocument::setHighlightWarning(bool has)
+{
+    d->m_hasHighlightWarning = has;
+}
+
 } // namespace TextEditor
 
 #include "basetextdocument.moc"