Splits up dependent load in update of allocation stats.

Splits up dependent loads in update of allocation stats.

Also uses strd for object and array initizlization.

Only on ARM for now. Together, these changes reduce the
number of profiler ticks in allocation stubs ~20%, and give a
small improvement on some benchmarks.

R=johnmccutchan@google.com, regis@google.com

Committed: https://code.google.com/p/dart/source/detail?r=40852

[zra, 2014-10-01 18:21:44]

zra@google.com changed reviewers:
+ johnmccutchan@google.com, regis@google.com

[regis, 2014-10-01 18:46:41]

LGTM

[Cutch, 2014-10-01 19:46:06]

lgtm

[zra, 2014-10-01 19:47:47]

Committed patchset #1 (id:1) manually as r40852 (presubmit successful).