(minor) snakview value() didn't update view in all cases

When setting a new value in the Snakview, the view didn't update in case the Snak type didn't
change but a new property ID was set.

Change-Id: Icc40d4cf00fe4152c2f456bf1f49267940bc315f
Merge "(minor) snakview value() didn't update view in all cases"