Support ES6 weak collections in heap profiler

BUG=chromium:376196
LOG=Y
R=alph@chromium.org, yangguo@chromium.org

Review URL: https://codereview.chromium.org/294163005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21460 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Revert "Make v8::TryCatch able to consume natively thrown exceptions (again)."

TBR=machenbach@chromium.org

Review URL: https://codereview.chromium.org/296133013

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21461 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Tiny steps towards a non-local 'Merge removable simulates' phase.

Distinguish copying/merging of the state. Better tracing.

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/299883003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21462 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Skip dead blocks/instructions in store elimination.

Also improve tracing.

R=ishell@chromium.org

Review URL: https://codereview.chromium.org/297933002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21463 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merge remote-tracking branch 'upstream/master'