Reland "Suppress canonicalization of Unbox() instruction that can deoptimize."

Reland "Suppress canonicalization of Unbox() instruction that can deoptimize."

This relands commit r41693 with additional fixes in canonicalization pass.

R=fschneider@google.com
BUG=

Committed: https://code.google.com/p/dart/source/detail?r=41736

[Florian Schneider, 2014-11-13 15:47:06]

https://codereview.chromium.org/726593002/diff/1/runtime/vm/intermediate_lang...
File runtime/vm/intermediate_language.cc (right):

https://codereview.chromium.org/726593002/diff/1/runtime/vm/intermediate_lang...
runtime/vm/intermediate_language.cc:2037: if (!HasUses()) return NULL;
Also check for CanDeoptimize() here?

[Vyacheslav Egorov (Google), 2014-11-13 18:20:20]

PTAL

This includes range analysis fixes and more tests.

[Florian Schneider, 2014-11-14 10:32:26]

LGTM.

Maybe we should assert that if can_overflow is true, at least one of min- or
max-boundary must be infinity (or unknown) for all arithmetic instructions.

[Vyacheslav Egorov (Google), 2014-11-14 11:19:50]

Committed patchset #3 (id:40001) manually as 41736 (presubmit successful).