Drawer edge swipe convers entire screen
Drawer edge swipe convers entire screen

When I tightened up the layout constraints for the Drawer in the
Scaffold, I ended up making the edge swipe detector cover the entire
screen.  This patch fixes that issue by putting the gesture detector for
the edge swipe just around the container with the proper width. We now
use a global key to maintain the state across hierarchy changes.

cbracken/flutter,flutter/flutter,cbracken/flutter,turnidge/flutter,tvolkert/flutter,cbracken/flutter,tvolkert/flutter,flutter/flutter,flutter/flutter,cbracken/flutter,Hixie/flutter,aghassemi/flutter,Hixie/flutter,aghassemi/flutter,tvolkert/flutter,cbracken/flutter,turnidge/flutter,flutter/flutter,tvolkert/flutter,Hixie/flutter,flutter/flutter,aghassemi/flutter,flutter/flutter,Hixie/flutter,Hixie/flutter,flutter/flutter,turnidge/flutter,aghassemi/flutter,turnidge/flutter,cbracken/flutter,tvolkert/flutter,cbracken/flutter,Hixie/flutter,Hixie/flutter,flutter/flutter,flutter/flutter,cbracken/flutter,flutter/flutter,cbracken/flutter,turnidge/flutter,tvolkert/flutter,tvolkert/flutter,Hixie/flutter,tvolkert/flutter,cbracken/flutter,Hixie/flutter,Hixie/flutter,tvolkert/flutter,tvolkert/flutter