Fix a couple problems with DownloadItemGtk.
Fix a couple problems with DownloadItemGtk.

1) We were crashing after removing a download item because g_signal_handler_find() was not working as expected.
2) We had a graphical glitch with the dangerous download dialog because GtkAlignments doesn't normally redraw on allocate.

BUG=13659
Review URL: http://codereview.chromium.org/118403

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@18132 0039d316-1c4b-4281-b951-d872f2087c98

ropik/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,adobe/chromium,yitian134/chromium,gavinp/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,adobe/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,ropik/chromium,gavinp/chromium,ropik/chromium,yitian134/chromium,ropik/chromium,adobe/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,ropik/chromium,adobe/chromium,ropik/chromium,gavinp/chromium,gavinp/chromium,ropik/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,ropik/chromium,yitian134/chromium,gavinp/chromium,adobe/chromium,adobe/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,adobe/chromium,ropik/chromium,gavinp/chromium,yitian134/chromium