Make asan and lsan make flags work like on the bots.

BUG=
R=ishell@chromium.org, jkummerow@chromium.org

Review URL: https://codereview.chromium.org/631763003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24419 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Don't use identity as hash function for integers.

Also slightly improve hashing of floats/doubles.

TEST=unittests
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/632713002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24420 ce2b1a6d-e550-0410-aec6-3dcde31c8c00