Adding laydom.c for the DOM build.

cmd/winfe/mkfiles32/mozilla.mak

@@ -886,6 +886,9 @@ $(OUTDIR)\mozilla.dep: $(DEPTH)\cmd\winfe\mkfiles32\mozilla.mak
 	$(DEPTH)\lib\layout\laycell.c
 	$(DEPTH)\lib\layout\laycols.c
 	$(DEPTH)\lib\layout\laydisp.c
+!if defined(DOM)
+	$(DEPTH)\lib\layout\laydom.c
+!endif
 	$(DEPTH)\lib\layout\layembed.c
 	$(DEPTH)\lib\layout\layfind.c
 	$(DEPTH)\lib\layout\layform.c