everything reset by ImplClear is going to be overwritten anyway

Change-Id: I94de8723a43d177fdf2caf0d8d3e529200d2e718

vcl/source/gdi/impgraph.cxx

@@ -183,8 +183,6 @@ ImpGraphic& ImpGraphic::operator=( const ImpGraphic& rImpGraphic )
 {
     if( &rImpGraphic != this )
     {
-        ImplClear();
-
         maMetaFile = rImpGraphic.maMetaFile;
         meType = rImpGraphic.meType;
         mnSizeBytes = rImpGraphic.mnSizeBytes;