Reify all blocks as syntactic blocks

Previous version of the pattern wasn't precise enough due to the
fact that synthetic units are now erased by syntactic block and
this could cause incorrect reification for cases like:

   val x = { val y = 1 }

Here syntactic block would extract one element but we still need to
reify it through syntactic block endpoint. So we can't filter based
on the number of elements extracted but rather filter on type of a
tree.