r144527 broke this when skipped all raw pointers in the memory instrumentation traversal algorithm. No we don't see JS externals strings in the native memory snapshot.
Created attachment 196149 [details] Patch
Comment on attachment 196149 [details] Patch LGTM
Comment on attachment 196149 [details] Patch Clearing flags on attachment: 196149 Committed r147466: <http://trac.webkit.org/changeset/147466>
All reviewed patches have been landed. Closing bug.