The BACKTRACE() macro currently checks whether NDEBUG is defined in the implementation of WTFReportBacktrace, and not in the BACKTRACE() macro. This means you need a Debug JavaScriptCore in order for it to do anything. It seems the check should be moved to the header file, so you can use BACKTRACE() in a WebCore debug build and not need a Debug JavaScriptCore, similar to the way the other macros like ASSERT() work.
Created attachment 89337 [details] Proposed patch
Comment on attachment 89337 [details] Proposed patch Looks great.
Comment on attachment 89337 [details] Proposed patch Clearing flags on attachment: 89337 Committed r83709: <http://trac.webkit.org/changeset/83709>
All reviewed patches have been landed. Closing bug.