Make SkTDArray accessors const-friendly

Make SkTDArray accessors const-friendly.

This change creates const and non-const versions of SkTDArray::begin(), end(), operator[]() and getAt(). This will keep us from inadvertently changing a const SkTDArray, which the previous signatures allowed.

Committed: http://code.google.com/p/skia/source/detail?r=7902

[jvanverth1, 2013-02-27 16:08:21]

(it's not clear to me that we need getAt(), but I wasn't sure of the
ramifications of removing it)

[jvanverth1, 2013-02-27 16:14:06]

On 2013/02/27 16:08:21, JimVV wrote:
> (it's not clear to me that we need getAt(), but I wasn't sure of the
> ramifications of removing it)

Nm, I see that it's useful for pointers to arrays.

[bsalomon, 2013-02-27 18:45:45]

On 2013/02/27 16:14:06, JimVV wrote:
> On 2013/02/27 16:08:21, JimVV wrote:
> > (it's not clear to me that we need getAt(), but I wasn't sure of the
> > ramifications of removing it)
> 
> Nm, I see that it's useful for pointers to arrays.

lgtm

[commit-bot: I haz the power, 2013-02-27 19:52:42]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/jvanverth@google.com/12315131/1

[commit-bot: I haz the power, 2013-02-27 19:52:48]

Presubmit check for 12315131-1 failed and returned exit status 1.

INFO:root:Found 11 file(s).
Running presubmit commit checks ...
Running /b/commit-queue/workdir/skia/PRESUBMIT.py

** Presubmit Warnings **
Tree state is: caution

***************
Tree is caution : junov committing change that affects DEPS roll - RP will
rebaseline ANGLE images
http://skia-tree-status.appspot.com/banner-status?format=json
***************

[commit-bot: I haz the power, 2013-02-28 19:03:00]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/jvanverth@google.com/12315131/1

[commit-bot: I haz the power, 2013-02-28 19:03:17]

Change committed as 7902