Add missing NULL check to TypeFeedbackOracle::CompareTypes()

R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/17096003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15167 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Improved range analysis for bitwise operations.

R=fschneider@chromium.org, verwaest@chromium.org

Review URL: https://chromiumcodereview.appspot.com/9156001

Patch from Stephen Adams <sra@google.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15170 ce2b1a6d-e550-0410-aec6-3dcde31c8c00