Bugfixes and improvements in escape analysis include:
* Handling of ObjectIsSmi (non-escaping)
* Handling of nested phi replacements
* Handling of phis with arity > 2
* Resilience against effectful nodes dangling from start
* Allocations escape now, if non-const load/store is performed
* Fixed a bug where non-allocated objects where tracked
* Allow fixed double arrays to be tracked
R=mstarzinger@chromium.org
BUG=v8:4586
LOG=n
Review URL: https://codereview.chromium.org/1510973006
Cr-Commit-Position: refs/heads/master@{#32833}
