Harden IsMoreGeneralElementsKindTransition.

R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/213783004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20489 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Do not mark prototype transitions link as weak in heap snapshot.

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/223643004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20490 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merge remote-tracking branch 'upstream/bleeding_edge' into bleeding_edge