Update VE core submodule to latest master (74353d9)

New changes:
af131d3 Clean up ve.dm.SurfaceFragment#isolateAndUnwrap a bit
b064ae8 Convert language name to lower case when looking for i18n file
f16dcac Fix ve.dm.SurfaceFragment#getSelectedNode
0fe1152 Clean up lots of minor things in SurfaceFragment
aec3043 Add excludeInsertion to translateRange()
f930950 Add excludeInsertion property to SurfaceFragment
a7ddd89 Exclude insertions in ve.dm.SurfaceFragment#isolateAndUnwrap
8108a0f Remove zh-[hk|tw] in favour of zh-han[s|t]
74353d9 Update OOjs UI to v0.1.0-pre (729c7bbe31)

Bug: 63828
Change-Id: I7aaebb071d544aec069d5ddab68740d93aed5bf4
(cherry picked from commit aeec009c147c3a9ffe5359e093c094226149b059)