Adding command to get accessibility elements tree
Adding command to get accessibility elements tree

Summary: This diffs adds Web Driver Agent commands that allows logging accessibility tree

Reviewed By: marekcirkos

Differential Revision: D3328940

fbshipit-source-id: b48b1725e8b80f973da986498f4d467681b8a906

b1ueshad0w/WebDriverAgent,riccoyu/WebDriverAgent,qa-dev/WebDriverAgent,Gogle/WebDriverAgent,drptbl/WebDriverAgent,zenzhu/WebDriverAgent,qa-dev/WebDriverAgent,drptbl/WebDriverAgent,zenzhu/WebDriverAgent,riccoyu/WebDriverAgent,calabash/WebDriverAgent,ymin/WebDriverAgent,Gogle/WebDriverAgent,drptbl/WebDriverAgent,PiranhaTeam/WebDriverAgent,ymin/WebDriverAgent,rafael-chavez/WebDriverAgent,calabash/WebDriverAgent,b1ueshad0w/WebDriverAgent,PiranhaTeam/WebDriverAgent,zenzhu/WebDriverAgent,riccoyu/WebDriverAgent,riccoyu/WebDriverAgent,qa-dev/WebDriverAgent,Gogle/WebDriverAgent,PiranhaTeam/WebDriverAgent,PiranhaTeam/WebDriverAgent,ymin/WebDriverAgent,b1ueshad0w/WebDriverAgent,qa-dev/WebDriverAgent,Gogle/WebDriverAgent,rafael-chavez/WebDriverAgent,PiranhaTeam/WebDriverAgent,calabash/WebDriverAgent,rafael-chavez/WebDriverAgent,ymin/WebDriverAgent,b1ueshad0w/WebDriverAgent