Update VE core submodule to master (a887989)

Also implement isInternetExplorer() in mw.Platform using jquery.client.

New changes:
9b2102f Skip over nested handlesOwnChildren nodes in getRelativeOffset
30a9835 Localisation updates from https://translatewiki.net.
5d142a0 Restrict get relative offset to movements of +/-1
7a2c984 Check that the surface has a selection after focus
851a63d Remove jquery.client
8786e53 Add evil detection functionality for IE
96f19ad Disable triple-click handling in IE
d746d42 Revert "Restrict get relative offset to movements of +/-1"
859d578 Revert "Skip over nested handlesOwnChildren nodes in getRelativeOffset"

Change-Id: Ib2e6568a862336e2516e4c519468218ec2a84834