navigating to 'Back' button

Change-Id: Iacc3e3e2770162877e63bccadb50c5fb1a73f0b1
Signed-off-by: Kalyan Prasad Tatavarthi <kalyan_prasad@in.ibm.com>
Reviewed-on: https://git.eclipse.org/r/c/jdt/eclipse.jdt.ui/+/184230
Tested-by: JDT Bot <jdt-bot@eclipse.org>
Tested-by: Noopur Gupta <noopur_gupta@in.ibm.com>
Reviewed-by: Noopur Gupta <noopur_gupta@in.ibm.com>