Don't use environment values at certain deoptimize-instructions.

Don't use environment values at certain deoptimize-instructions.

If a HDeoptimize does not cut away parts of the control-flow-graph
we don't need to insert uses to correctly elimiate dead phis since
the full function is visible to the optimizing compiler.

This is a small improvement of the change r7221 which fixed a problem
when deoptimizing on never executed case-clauses.
Committed: http://code.google.com/p/v8/source/detail?r=7877

[Vyacheslav Egorov (Chromium), 2011-05-12 14:32:59]

LGTM

http://codereview.chromium.org/7012010/diff/1/src/hydrogen.h
File src/hydrogen.h (right):

http://codereview.chromium.org/7012010/diff/1/src/hydrogen.h#newcode128
src/hydrogen.h:128: void FinishExitWithDeoptimization(bool use_environment) {
Can you use enum instead of boolean?