The current option --enable-debug-symbols adds -g, which uses the second level of debug information. For many cases the information added by the first level (-g1) is enough (getting a backtrace, for example) and it's the only way to build webkit with debug symbols in a 32 bit system.
Created attachment 171237 [details] Patch
Committed r132876: <http://trac.webkit.org/changeset/132876>