(bug 45651) Fix for snakview.isInitialSnak

Before this fix, the Toolbar didn't change when clicking "edit" on a Claim with a PropertyValue
main Snak which uses a data value type which doesn't match the Snak's Property's DataType's data
value type.

- patch set 2: fix for wb.Snak.prototype.equals. Can compare to non-Snak values now.

Change-Id: I179c161c8dbf97c2787a0fad0dda99637a8d42a4
Merge "(bug 45651) Fix for snakview.isInitialSnak"