[GTK] fix crash when dragging within process over render view.
[GTK] fix crash when dragging within process over render view.

The data is returned synchronously in gtk_drag_get_data(). We have to set the number of requests beforehand.

BUG=59304
TEST=drag bookmark from bookmark bar onto render view; no sad tab

Review URL: http://codereview.chromium.org/3830002

git-svn-id: http://src.chromium.org/svn/trunk/src@62688 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 96398526ec6db0620ef14e39bd1d0adfba2214ed
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser