GTK: Fix minor slide animation bugs.
GTK: Fix minor slide animation bugs.

Following r27934, we might hit the code path for initial positioning *after* the AnimationProgressed positioning, causing the child widget not to show.

BUG=23902
TEST=when you switch away from a tab that has an infobar, then switch back, you can see the infobar.

Review URL: http://codereview.chromium.org/258038

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@28214 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser