Use a label-branch in CheckConstPool.

Use a label-branch in CheckConstPool.

This removes a dependency on the size of the pool. Whilst the size is
checked in debug mode, it is still more robust to use a label.

This should also be cherry-picked to fix 4.4.63.20. (At that time, the
size of the pool was _not_ checked, and was sometimes wrong.)

This partially reverts 879550c, "[arm] Don't call branch_offset within
CheckConstPool." However, branch_offset now only blocks the constant
pool if it is not already blocked.

BUG=

Committed: https://crrev.com/bfe700b8edfe68e8c5f05d408f71168096bc2e1a
Cr-Commit-Position: refs/heads/master@{#29746}

[jbramley, 2015-07-17 16:13:35]

jacob.bramley@arm.com changed reviewers:
+ bmeurer@chromium.org, hablich@chromium.org

[Michael Hablich, 2015-07-20 07:41:00]

On 2015/07/17 at 16:13:35, jacob.bramley wrote:
> 

Should this also be merged into 4.5?

Can you please add Ulan as a reviewer, Benedikt is OOO the next few days.

[jbramley, 2015-07-20 08:11:52]

jacob.bramley@arm.com changed reviewers:
+ ulan@chromium.org, yangguo@chromium.org

[jbramley, 2015-07-20 08:13:55]

On 2015/07/20 07:41:00, Hablich wrote:
> On 2015/07/17 at 16:13:35, jacob.bramley wrote:
> > 
> 
> Should this also be merged into 4.5?

4.5 already has Yang's "Make sure the constant pool size is as promised."
(https://codereview.chromium.org/1217673003). That's the commit which makes the
constant pool size predictable, and it's what 4.4 lacked. However, backporting
it to 4.4 was much more complicated that this change, and I think we should be
using a label-branch here anyway.

[ulan, 2015-07-20 08:16:00]

lgtm

[jbramley, 2015-07-20 08:40:53]

The CQ bit was checked by jacob.bramley@arm.com

[commit-bot: I haz the power, 2015-07-20 08:40:57]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1227403006/1

[commit-bot: I haz the power, 2015-07-20 09:03:15]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-20 09:03:28]

Patchset 1 (id:??) landed as
https://crrev.com/bfe700b8edfe68e8c5f05d408f71168096bc2e1a
Cr-Commit-Position: refs/heads/master@{#29746}