Added {Zone}GrowableHandlePtrArray types: simplifies code, makes code safer

Added {Zone}GrowableHandlePtrArray types: simplifies code, makes code safer

BUG=
R=regis@google.com

Committed: https://github.com/dart-lang/sdk/commit/dd5410209f6fa4e4559a80c5aba5b0c9e48f9ffa

[srdjan, 2015-08-28 21:10:19]

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

[Florian Schneider, 2015-08-31 07:02:58]

fschneider@google.com changed reviewers:
+ fschneider@google.com

[Florian Schneider, 2015-08-31 07:02:59]

dbc

https://codereview.chromium.org/1312833009/diff/1/runtime/vm/growable_array.h
File runtime/vm/growable_array.h (right):

https://codereview.chromium.org/1312833009/diff/1/runtime/vm/growable_array.h...
runtime/vm/growable_array.h:205: // Use unique zone handles to store objects.
Why do the handles need to be unique?

I think you could only re-wrap if the handle is not a zone handle.

[srdjan, 2015-08-31 14:52:40]

https://codereview.chromium.org/1312833009/diff/1/runtime/vm/growable_array.h
File runtime/vm/growable_array.h (right):

https://codereview.chromium.org/1312833009/diff/1/runtime/vm/growable_array.h...
runtime/vm/growable_array.h:205: // Use unique zone handles to store objects.
On 2015/08/31 07:02:59, Florian Schneider wrote:
> Why do the handles need to be unique?
> 
> I think you could only re-wrap if the handle is not a zone handle.

Often, e.g., in a loop, we reuse the handles. This means that we could
accidentally overwrite the content of the handle stored in the array, unless the
caller takes extra precaution that the handle is not being reused (which is a
fragile assumption).  That kind of bug appeared several times before.

[regis, 2015-08-31 15:32:16]

LGTM

[srdjan, 2015-08-31 16:24:14]

Committed patchset #2 (id:20001) manually as
dd5410209f6fa4e4559a80c5aba5b0c9e48f9ffa (presubmit successful).