When TemplateHaskell language extension is enabled it is valid to have
top-level expressions.  Each such expression is treated as a contents
of a splice.  The problem arises with typed splices.  They are not valid
at the top level and therefore we should interpret them not as a splice
but as a top-level expression (aka. implicit splice).  So saying:

$$foo

is equivalent of:

$( $$foo )

This patch makes sure that this is indeed the case.  Until now we
incorrectly treated typed splices as explicit splices.