Provide default traits for PersistentValueMap
Re-try of issue
201643003. This caused linker errors on Win64, since the
linker insists on seeing the StrongMapTrait method implementations even
though they are never used. This will provide default implementations
for them.
R=dcarney@chromium.org
BUG=
Review URL: https://codereview.chromium.org/
204343006
Patch from Daniel Vogelheim <vogelheim@chromium.org>.
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20084
ce2b1a6d-e550-0410-aec6-
3dcde31c8c00