Implement KnownSuccessor method to some control instructions.

R=jkummerow@chromium.org
BUG=v8:3118
LOG=N

Review URL: https://codereview.chromium.org/174863002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19759 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Mark mjsunit/string-case as flaky.

BUG=v8:3208
LOG=N
R=machenbach@chromium.org

Review URL: https://codereview.chromium.org/192573004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19760 ce2b1a6d-e550-0410-aec6-3dcde31c8c00