Better place to initialize mnThemedIdx

To make 'if (rBackgroundFillStyle.mnThemedIdx != 0)' actually work
as intended. Avoids invalid call to pTheme->getFillStyle() which
is not supposed to return 0 here.

Change-Id: I323e2628cba64167240e8f0b945e6693b47b8e77

include/oox/drawingml/shape.hxx

@@ -50,6 +50,7 @@ struct ShapeStyleRef
 {
     Color               maPhClr;
     sal_Int32           mnThemedIdx;
+    ShapeStyleRef() : mnThemedIdx(0) {}
 };
 
 typedef ::std::map< sal_Int32, ShapeStyleRef > ShapeStyleRefMap;

oox/source/drawingml/table/tablebackgroundstylecontext.cxx

@@ -34,7 +34,6 @@ TableBackgroundStyleContext::TableBackgroundStyleContext( ContextHandler2Helper&
 : ContextHandler2( rParent )
 , mrTableStyle( rTableStyle )
 {
-    mrTableStyle.getBackgroundFillStyleRef().mnThemedIdx = 0;
 }
 
 TableBackgroundStyleContext::~TableBackgroundStyleContext()

oox/source/drawingml/table/tablecell.cxx

@@ -362,13 +362,8 @@ void TableCell::pushToXCell( const ::oox::core::XmlFilterBase& rFilterBase, ::oo
     {
         if (const Theme* pTheme = rFilterBase.getCurrentTheme())
         {
-            FillProperties const*const pStyle(
-                    pTheme->getFillStyle(rBackgroundFillStyle.mnThemedIdx));
-            if (pStyle)
-            {
-                aBgColor = pStyle->getBestSolidColor();
-                nPhClr = rBackgroundFillStyle.maPhClr.getColor(rFilterBase.getGraphicHelper());
-            }
+            aBgColor = pTheme->getFillStyle(rBackgroundFillStyle.mnThemedIdx)->getBestSolidColor();
+            nPhClr = rBackgroundFillStyle.maPhClr.getColor(rFilterBase.getGraphicHelper());
         }
     }
     if (aBgColor.isUsed())