fix StyleRef to Heading styles when doc is opened in localized MS Word

We need to use { styleref 1 } instead of { styleref "Heading 1" } etc.
to avoid the localization issues. Heading style names are localized
in MS Word, and reference would point to a non-existent style.

Change-Id: Ib74d67d265cf98962dfc6f328f08a236a95fae98
Reviewed-on: https://gerrit.libreoffice.org/19441
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Andras Timar <andras.timar@collabora.com>
diff --git a/sw/source/filter/ww8/ww8atr.cxx b/sw/source/filter/ww8/ww8atr.cxx
index 54e35d0..a7b7f9f 100644
--- a/sw/source/filter/ww8/ww8atr.cxx
+++ b/sw/source/filter/ww8/ww8atr.cxx
@@ -2877,9 +2877,9 @@ void AttributeOutputBase::TextField( const SwFormatField& rField )
                SwChapterField aCopy(*static_cast<const SwChapterField*>(pField));
                aCopy.ChangeExpansion(*pTextNd, false);
                const OUString sStr = FieldString(ww::eSTYLEREF)
                    + " \"Heading "
                    + " "
                    + OUString::number(aCopy.GetLevel() + 1)
                    + "\"  \\* MERGEFORMAT ";
                    + " \\* MERGEFORMAT ";
                GetExport().OutputField(pField, ww::eSTYLEREF, sStr);
                bWriteExpand = false;
            }