Alter the second hash used in StoreBuffer::Compact.
Alter the second hash used in StoreBuffer::Compact.

hash2 >> (kHashMapLengthLog2 * 2) was always zero because hash2 was masked with (kHashMapLength - 1).

R=erik.corry@gmail.com

Review URL: http://codereview.chromium.org/9085021

git-svn-id: b158db1e4b4ab85d4c9e510fdef4b1e8c614b15b@10336 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh