Tidy up m_wordfm.
First, as the allocator function does not fail, there is no need
to assert its return value.
Second, remove commented out (since r8765) function VG_(isEmptyFM).
Third, remove VG_(getNodeSizeFM) from the API. The details of the
implementation do not need to be exposed.
Fourth, for consistency require that the copy functions for keys and
values in VG_(dopyFM) (which are essentially like allocators) return
non-NULL values for non-NULL arguments if they return.
Fifth, document NULL-ness of return values for VG_(newFM), VG_(dopyFM),
and VG_(newBag). Remove pointless asserts at call sites.
Six, change avl_dopy to assert that the node the function is
supposed to copy is not NULL. It is called that way anyhow. With 
that change the function never returns NULL which allows us to
simplify the call sites. Checking the return value is no longer needed.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14535 a5019735-40e9-0310-863c-91ae7b9d1cf9
Document that VG_(newRangeMap) never returns NULL.
Remove pointless asserts.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14536 a5019735-40e9-0310-863c-91ae7b9d1cf9