Check if the size has been properly set.

For TTF outlines this is already handled, however,
for traditional CFF outlines the check happens too
late. We need to check early.

src/cff/cffgload.c

@@ -358,6 +358,13 @@
       FT_UShort     advanceX;
       FT_UShort     advanceY;
 
+      if ( ( size->root.metrics.x_ppem < 1 ||
+             size->root.metrics.y_ppem < 1 ) )
+      {
+        error = FT_THROW( Invalid_Size_Handle );
+        return error;
+      }
+
       FT_TRACE3(( "Attemping to load SVG glyph\n" ));
       sfnt = (SFNT_Service)((TT_Face)glyph->root.face)->sfnt;
       error = sfnt->load_svg_doc( (FT_GlyphSlot)glyph, glyph_index );