Some more speedup to the dominators tree building in heap profiler.
Some more speedup to the dominators tree building in heap profiler.

Replace timestamps with affected bool vector. Timestamps could cause
some entries marked as affected on iteration i, to be recalculated
twice on iterations i and i+1. Which is redundant.

BUG=none
TEST=none

Review URL: https://chromiumcodereview.appspot.com/9467002
Patch from Alexei Filippov <alexeif@chromium.org>.

git-svn-id: b158db1e4b4ab85d4c9e510fdef4b1e8c614b15b@10821 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh