Fix loading of toast app icons

We need an application context for icons, and a display
context for layout.

Test: ToastTest (all 5 matches with atest)
Test: InternetDialogDelegateControllerTest
Test: post toast from Settings
Flag: EXEMPT bug fix
Fixes: 372190414
Change-Id: Ia2ad158adb647706342211f13336a29c39c986e6