This is the first part of escape analysis for turbofan.
At the moment, there is no deopt support, and support
for loops is partial (only binary Phis are handled).
The CL includes 4 unittests.
There are also 8 new mjsunit tests, some of which are
skiped as they require features not yet implemented.
BUG=v8:4586
LOG=n
Review URL: https://codereview.chromium.org/1457683003
Cr-Commit-Position: refs/heads/master@{#32498}
