Cache initial (empty) ic_data arrays so that they are not repeatedly allocated. Factor out descript…

Cache initial (empty) ic_data arrays so that they are not repeatedly allocated. Factor out descriptor and data array allocation. Will be used later when we copy the descriptor for background compilation.

BUG=
R=asiva@google.com

Committed: https://github.com/dart-lang/sdk/commit/cea892f234ee85ac1fb1cf3e2983d816e300aaf0

[srdjan, 2015-10-27 18:27:08]

srdjan@google.com changed reviewers:
+ asiva@google.com

[siva, 2015-10-27 21:32:44]

LGTM with one comment.

https://codereview.chromium.org/1410573006/diff/20001/runtime/vm/object.cc
File runtime/vm/object.cc (right):

https://codereview.chromium.org/1410573006/diff/20001/runtime/vm/object.cc#ne...
runtime/vm/object.cc:12634: WriteSentinel(array, len);
Array should be made immutable after the sentinel values have been written to?

[srdjan, 2015-10-27 21:53:18]

https://codereview.chromium.org/1410573006/diff/20001/runtime/vm/object.cc
File runtime/vm/object.cc (right):

https://codereview.chromium.org/1410573006/diff/20001/runtime/vm/object.cc#ne...
runtime/vm/object.cc:12634: WriteSentinel(array, len);
On 2015/10/27 21:32:44, siva wrote:
> Array should be made immutable after the sentinel values have been written to?

Done. It should have crashed, Siva is fixing it.

[srdjan, 2015-10-27 22:05:29]

Committed patchset #3 (id:40001) manually as
cea892f234ee85ac1fb1cf3e2983d816e300aaf0 (presubmit successful).