remove unused DocTreeNode::NodeType::Invalid

Change-Id: I68dde9c81ac73875382cd09bf342340b6c144ee8
Reviewed-on: https://gerrit.libreoffice.org/63935
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

compilerplugins/clang/unusedenumconstants.readonly.results

@@ -1232,8 +1232,6 @@ slideshow/source/engine/slideview.cxx:249
     enum slideshow::internal::(anonymous namespace)::LayerSpriteContainer::(anonymous at /home/noel/libo2/slideshow/source/engine/slideview.cxx:249:5) SPRITE_ULLAGE
 slideshow/source/engine/slideview.cxx:729
     enum slideshow::internal::(anonymous namespace)::SlideView::(anonymous at /home/noel/libo2/slideshow/source/engine/slideview.cxx:729:5) LAYER_ULLAGE
-slideshow/source/inc/doctreenode.hxx:52
-    enum slideshow::internal::DocTreeNode::NodeType Invalid
 soltools/cpp/cpp.h:42
     int WS
 svgio/inc/svgstyleattributes.hxx:62

slideshow/source/engine/shapes/drawshapesubsetting.cxx

@@ -604,8 +604,6 @@ namespace slideshow
             {
                 switch( eNodeType )
                 {
-                    case DocTreeNode::NodeType::Invalid:
-                        // FALLTHROUGH intended
                     default:
                         SAL_WARN( "slideshow", "DrawShapeSubsetting::mapDocTreeNode(): unexpected node type");
                         return DrawShapeSubsetting::CLASS_NOOP;

slideshow/source/inc/doctreenode.hxx

@@ -49,8 +49,6 @@ namespace slideshow
             /// Type of shape entity represented by this node
             enum class NodeType
             {
-                Invalid=0,
-
                 /// This node represents a paragraph
                 LogicalParagraph=129,
                 /// This node represents a word