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: de016e52bd170d2d4f2344f9bf92d50478b649e0@28214 0039d316-1c4b-4281-b951-d872f2087c98

crosswalk-project/chromium-crosswalk-efl,jaruba/chromium.src,dednal/chromium.src,mohamed--abdel-maksoud/chromium.src,krieger-od/nwjs_chromium.src,hgl888/chromium-crosswalk,hgl888/chromium-crosswalk,mogoweb/chromium-crosswalk,crosswalk-project/chromium-crosswalk-efl,markYoungH/chromium.src,TheTypoMaster/chromium-crosswalk,rogerwang/chromium,M4sse/chromium.src,jaruba/chromium.src,Pluto-tv/chromium-crosswalk,mohamed--abdel-maksoud/chromium.src,ltilve/chromium,keishi/chromium,hujiajie/pa-chromium,timopulkkinen/BubbleFish,mogoweb/chromium-crosswalk,Jonekee/chromium.src,Fireblend/chromium-crosswalk,crosswalk-project/chromium-crosswalk-efl,timopulkkinen/BubbleFish,zcbenz/cefode-chromium,Pluto-tv/chromium-crosswalk,anirudhSK/chromium,jaruba/chromium.src,pozdnyakov/chromium-crosswalk,rogerwang/chromium,robclark/chromium,anirudhSK/chromium,bright-sparks/chromium-spacewalk,robclark/chromium,dednal/chromium.src,hgl888/chromium-crosswalk,hujiajie/pa-chromium,zcbenz/cefode-chromium,mohamed--abdel-maksoud/chromium.src,keishi/chromium,crosswalk-project/chromium-crosswalk-efl,keishi/chromium,Jonekee/chromium.src,ChromiumWebApps/chromium,pozdnyakov/chromium-crosswalk,Fireblend/chromium-crosswalk,chuan9/chromium-crosswalk,markYoungH/chromium.src,anirudhSK/chromium,dushu1203/chromium.src,Fireblend/chromium-crosswalk,robclark/chromium,Just-D/chromium-1,M4sse/chromium.src,Jonekee/chromium.src,hgl888/chromium-crosswalk-efl,ondra-novak/chromium.src,zcbenz/cefode-chromium,markYoungH/chromium.src,PeterWangIntel/chromium-crosswalk,rogerwang/chromium,zcbenz/cefode-chromium,ltilve/chromium,zcbenz/cefode-chromium,axinging/chromium-crosswalk,hujiajie/pa-chromium,krieger-od/nwjs_chromium.src,Just-D/chromium-1,zcbenz/cefode-chromium,jaruba/chromium.src,axinging/chromium-crosswalk,hujiajie/pa-chromium,dushu1203/chromium.src,junmin-zhu/chromium-rivertrail,timopulkkinen/BubbleFish,timopulkkinen/BubbleFish,junmin-zhu/chromium-rivertrail,PeterWangIntel/chromium-crosswalk,littlstar/chromium.src,hujiajie/pa-chromium,jaruba/chromium.src,axinging/chromium-crosswalk,fujunwei/chromium-crosswalk,dednal/chromium.src,ondra-novak/chromium.src,hujiajie/pa-chromium,TheTypoMaster/chromium-crosswalk,littlstar/chromium.src,dushu1203/chromium.src,junmin-zhu/chromium-rivertrail,krieger-od/nwjs_chromium.src,mogoweb/chromium-crosswalk,zcbenz/cefode-chromium,crosswalk-project/chromium-crosswalk-efl,mogoweb/chromium-crosswalk,chuan9/chromium-crosswalk,ChromiumWebApps/chromium,bright-sparks/chromium-spacewalk,keishi/chromium,chuan9/chromium-crosswalk,Chilledheart/chromium,krieger-od/nwjs_chromium.src,patrickm/chromium.src,dednal/chromium.src,M4sse/chromium.src,bright-sparks/chromium-spacewalk,keishi/chromium,timopulkkinen/BubbleFish,hgl888/chromium-crosswalk,ChromiumWebApps/chromium,M4sse/chromium.src,rogerwang/chromium,littlstar/chromium.src,markYoungH/chromium.src,hgl888/chromium-crosswalk-efl,keishi/chromium,mohamed--abdel-maksoud/chromium.src,junmin-zhu/chromium-rivertrail,rogerwang/chromium,Fireblend/chromium-crosswalk,ondra-novak/chromium.src,rogerwang/chromium,dushu1203/chromium.src,hgl888/chromium-crosswalk-efl,nacl-webkit/chrome_deps,ondra-novak/chromium.src,mogoweb/chromium-crosswalk,dushu1203/chromium.src,markYoungH/chromium.src,TheTypoMaster/chromium-crosswalk,mogoweb/chromium-crosswalk,axinging/chromium-crosswalk,krieger-od/nwjs_chromium.src,nacl-webkit/chrome_deps,anirudhSK/chromium,Jonekee/chromium.src,bright-sparks/chromium-spacewalk,crosswalk-project/chromium-crosswalk-efl,nacl-webkit/chrome_deps,mohamed--abdel-maksoud/chromium.src,mogoweb/chromium-crosswalk,fujunwei/chromium-crosswalk,M4sse/chromium.src,axinging/chromium-crosswalk,markYoungH/chromium.src,ChromiumWebApps/chromium,markYoungH/chromium.src,TheTypoMaster/chromium-crosswalk,Jonekee/chromium.src,bright-sparks/chromium-spacewalk,chuan9/chromium-crosswalk,littlstar/chromium.src,hgl888/chromium-crosswalk,chuan9/chromium-crosswalk,anirudhSK/chromium,anirudhSK/chromium,markYoungH/chromium.src,littlstar/chromium.src,crosswalk-project/chromium-crosswalk-efl,ondra-novak/chromium.src,timopulkkinen/BubbleFish,dushu1203/chromium.src,bright-sparks/chromium-spacewalk,markYoungH/chromium.src,hujiajie/pa-chromium,rogerwang/chromium,Pluto-tv/chromium-crosswalk,bright-sparks/chromium-spacewalk,mohamed--abdel-maksoud/chromium.src,hgl888/chromium-crosswalk-efl,M4sse/chromium.src,TheTypoMaster/chromium-crosswalk,fujunwei/chromium-crosswalk,fujunwei/chromium-crosswalk,junmin-zhu/chromium-rivertrail,keishi/chromium,anirudhSK/chromium,ChromiumWebApps/chromium,nacl-webkit/chrome_deps,zcbenz/cefode-chromium,krieger-od/nwjs_chromium.src,chuan9/chromium-crosswalk,nacl-webkit/chrome_deps,ltilve/chromium,rogerwang/chromium,zcbenz/cefode-chromium,axinging/chromium-crosswalk,robclark/chromium,timopulkkinen/BubbleFish,Chilledheart/chromium,patrickm/chromium.src,nacl-webkit/chrome_deps,Pluto-tv/chromium-crosswalk,pozdnyakov/chromium-crosswalk,keishi/chromium,patrickm/chromium.src,Chilledheart/chromium,krieger-od/nwjs_chromium.src,fujunwei/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,pozdnyakov/chromium-crosswalk,nacl-webkit/chrome_deps,junmin-zhu/chromium-rivertrail,robclark/chromium,dednal/chromium.src,axinging/chromium-crosswalk,chuan9/chromium-crosswalk,pozdnyakov/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,zcbenz/cefode-chromium,timopulkkinen/BubbleFish,mogoweb/chromium-crosswalk,Just-D/chromium-1,ChromiumWebApps/chromium,M4sse/chromium.src,markYoungH/chromium.src,M4sse/chromium.src,zcbenz/cefode-chromium,TheTypoMaster/chromium-crosswalk,ChromiumWebApps/chromium,pozdnyakov/chromium-crosswalk,Pluto-tv/chromium-crosswalk,rogerwang/chromium,patrickm/chromium.src,crosswalk-project/chromium-crosswalk-efl,hujiajie/pa-chromium,nacl-webkit/chrome_deps,dednal/chromium.src,mohamed--abdel-maksoud/chromium.src,Jonekee/chromium.src,junmin-zhu/chromium-rivertrail,littlstar/chromium.src,ondra-novak/chromium.src,jaruba/chromium.src,robclark/chromium,Fireblend/chromium-crosswalk,patrickm/chromium.src,markYoungH/chromium.src,timopulkkinen/BubbleFish,ltilve/chromium,Chilledheart/chromium,keishi/chromium,dushu1203/chromium.src,Chilledheart/chromium,ltilve/chromium,M4sse/chromium.src,mohamed--abdel-maksoud/chromium.src,Just-D/chromium-1,Jonekee/chromium.src,krieger-od/nwjs_chromium.src,jaruba/chromium.src,fujunwei/chromium-crosswalk,jaruba/chromium.src,anirudhSK/chromium,jaruba/chromium.src,pozdnyakov/chromium-crosswalk,Pluto-tv/chromium-crosswalk,hgl888/chromium-crosswalk-efl,axinging/chromium-crosswalk,hgl888/chromium-crosswalk-efl,mogoweb/chromium-crosswalk,crosswalk-project/chromium-crosswalk-efl,timopulkkinen/BubbleFish,Fireblend/chromium-crosswalk,keishi/chromium,jaruba/chromium.src,pozdnyakov/chromium-crosswalk,Chilledheart/chromium,robclark/chromium,junmin-zhu/chromium-rivertrail,robclark/chromium,chuan9/chromium-crosswalk,ltilve/chromium,pozdnyakov/chromium-crosswalk,ondra-novak/chromium.src,dednal/chromium.src,Fireblend/chromium-crosswalk,nacl-webkit/chrome_deps,bright-sparks/chromium-spacewalk,Just-D/chromium-1,ltilve/chromium,mohamed--abdel-maksoud/chromium.src,pozdnyakov/chromium-crosswalk,patrickm/chromium.src,hujiajie/pa-chromium,hujiajie/pa-chromium,junmin-zhu/chromium-rivertrail,Chilledheart/chromium,PeterWangIntel/chromium-crosswalk,pozdnyakov/chromium-crosswalk,patrickm/chromium.src,Just-D/chromium-1,hgl888/chromium-crosswalk,Jonekee/chromium.src,PeterWangIntel/chromium-crosswalk,hgl888/chromium-crosswalk-efl,hgl888/chromium-crosswalk-efl,Just-D/chromium-1,ChromiumWebApps/chromium,mohamed--abdel-maksoud/chromium.src,M4sse/chromium.src,anirudhSK/chromium,patrickm/chromium.src,Chilledheart/chromium,ondra-novak/chromium.src,dushu1203/chromium.src,Pluto-tv/chromium-crosswalk,chuan9/chromium-crosswalk,Just-D/chromium-1,PeterWangIntel/chromium-crosswalk,dushu1203/chromium.src,PeterWangIntel/chromium-crosswalk,krieger-od/nwjs_chromium.src,dednal/chromium.src,timopulkkinen/BubbleFish,axinging/chromium-crosswalk,junmin-zhu/chromium-rivertrail,fujunwei/chromium-crosswalk,axinging/chromium-crosswalk,Fireblend/chromium-crosswalk,dushu1203/chromium.src,ChromiumWebApps/chromium,krieger-od/nwjs_chromium.src,Jonekee/chromium.src,rogerwang/chromium,hgl888/chromium-crosswalk,patrickm/chromium.src,dednal/chromium.src,keishi/chromium,Just-D/chromium-1,hgl888/chromium-crosswalk-efl,PeterWangIntel/chromium-crosswalk,littlstar/chromium.src,ChromiumWebApps/chromium,anirudhSK/chromium,ltilve/chromium,hgl888/chromium-crosswalk-efl,ChromiumWebApps/chromium,TheTypoMaster/chromium-crosswalk,bright-sparks/chromium-spacewalk,ondra-novak/chromium.src,Pluto-tv/chromium-crosswalk,Chilledheart/chromium,hgl888/chromium-crosswalk,dushu1203/chromium.src,krieger-od/nwjs_chromium.src,Pluto-tv/chromium-crosswalk,fujunwei/chromium-crosswalk,mohamed--abdel-maksoud/chromium.src,Jonekee/chromium.src,robclark/chromium,jaruba/chromium.src,hgl888/chromium-crosswalk,dednal/chromium.src,Jonekee/chromium.src,nacl-webkit/chrome_deps,littlstar/chromium.src,ChromiumWebApps/chromium,mogoweb/chromium-crosswalk,fujunwei/chromium-crosswalk,junmin-zhu/chromium-rivertrail,nacl-webkit/chrome_deps,axinging/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,anirudhSK/chromium,Fireblend/chromium-crosswalk,anirudhSK/chromium,PeterWangIntel/chromium-crosswalk,dednal/chromium.src,ltilve/chromium,robclark/chromium,M4sse/chromium.src,hujiajie/pa-chromium