[GTK] Test gardening around MOUSE_CURSOR_SCALE.

[GTK] Test gardening around MOUSE_CURSOR_SCALE.
https://bugs.webkit.org/show_bug.cgi?id=109469

Patch by Ms2ger <Ms2ger@igalia.com> on 2017-08-04
Reviewed by Carlos Alberto Lopez Perez.

Remove obsolete expectation for cursor-parsing-image-set.html; it may have
started passing in r209396.

Mark mouse-cursor-image-set.html as failing rather than using an incorrect
-expected file.

* platform/gtk/TestExpectations:
* platform/gtk/fast/events/mouse-cursor-image-set-expected.txt: Removed.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@220266 268f45cc-cd09-0410-ab3c-d52691b4dbfc