Revert "Derive synthetic type bounds for expressions"

TBR=jkummerow@chromium.org
BUG=

Review URL: https://codereview.chromium.org/18524002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15443 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Revert "Remove BinaryOp::result_type"

This reverts https://code.google.com/p/v8/source/detail?r=15265, due to performance regression.

TBR=jkummerow@chromium.org
BUG=

Review URL: https://codereview.chromium.org/18525002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15444 ce2b1a6d-e550-0410-aec6-3dcde31c8c00