Integrate branch of IAccessible2

(cherry picked from commit e2f90c93c97f3cf137c348ed302c6470f398aa70)

Change-Id: I44ce0d69f3e7364038b00b1ba0f0d27e60132a37

WaE: Prevent uninitialized variable warnings.

(cherry picked from commit b989f4074ea70729d527b307bfbe49e01a0d3646)
Document::ProcessWindowEvent now just forwards to baseclass

Change-Id: Ia4c224105e15c8eea90a9c98161981ff10661044