Bug 703888 - Remove dom/Makefile.in comment leftover from bug 533891; r=ted

dom/Makefile.in

@@ -85,10 +85,6 @@ DIRS += \
 
 ifdef ENABLE_TESTS
 DIRS += tests
-
-# These subdirs rely on GTK libraries and header files, it is not
-#  buildable on other non-GTK unix builds
-
 ifneq (,$(filter gtk2 cocoa windows android qt os2,$(MOZ_WIDGET_TOOLKIT)))
 DIRS += plugins/test
 endif