Merged r15898 into trunk branch.

Revert "Check that ExternalString objects get aligned resources" (r15894).

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/20560006

git-svn-id: https://v8.googlecode.com/svn/trunk@15899 ce2b1a6d-e550-0410-aec6-3dcde31c8c00