[gtk+] Drop a no-longer-working test

[Matthias Clasen <matthiasc src gnome org>]

commit c0cd46355d66f180afc417aa85fbd4c827166f58
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Dec 31 12:51:54 2017 -0500

    Drop a no-longer-working test
    
    Embedding toplevels does not work anymore.

 tests/meson.build         |    1 -
 tests/testtoplevelembed.c |  104 ---------------------------------------------
 2 files changed, 0 insertions(+), 105 deletions(-)
---
diff --git a/tests/meson.build b/tests/meson.build
index 911e195..988f2c4 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -101,7 +101,6 @@ gtk_tests = [
   ['testscrolledge'],
   ['testcellarea'],
   ['testswitch'],
-  ['testtoplevelembed'],
   ['testnoscreen'],
   ['testtreepos'],
   ['testsensitive'],