Don't assign safepoint at the definition to the definition's live-range.

Don't assign safepoint at the definition to the definition's live-range.

This avoids treating spill slot associated with the definition live during GC as
it will only be filled in after definition's code is fully executed.

Additionally this makes output register dead for GC inside the definiton itself
which is something we used to guarantee manually by removing it from the
live_registers set before calling on the slow path.

BUG=
R=fschneider@google.com

Committed: https://code.google.com/p/dart/source/detail?r=38059

[Vyacheslav Egorov (Google), 2014-07-07 23:41:49]

PTAL

As discussed in the meeting, this is both repro and the fix. I had to introduce
a flag to trigger mandatory GC at (runtime) allocation of instances of the given
class otherwise it is very hard to write a test case.

I need to figure out how to set expectations correctly as this test will only be
meaningful in DEBUG mode (as I made the flag debug only).

[Florian Schneider, 2014-07-08 12:29:02]

LGTM. I think you can mark it as Crash in Debug mode, and maybe  Pass/Crash in
release mode, since it may actually crash if a GC happens at the right time.

[Vyacheslav Egorov (Google), 2014-07-08 14:12:12]

Committed patchset #1 manually as r38059 (presubmit successful).

[srdjan, 2014-07-08 22:28:03]

lgtm