Change drawText() to generate positions and send to drawPosText()

Change drawText() to generate positions and send to drawPosText()

The idea here is to have a central place that does layout for drawText(), and
then always feed text through drawPosText(). This both makes all of the 
GrTextContexts consistent in drawText() output, and does a better job of
stressing drawPosText().

Because of the effect of matrices on hinting and approximation error, the 
generated text is not 100% identical to that produced by the raster pipeline.

BUG=skia:2887
Committed: https://skia.googlesource.com/skia/+/7851a56895c9c076f73a835a7dd51d3c6180c16f

[jvanverth1, 2014-10-15 21:07:33]

jvanverth@google.com changed reviewers:
+ bungeman@google.com, cdalton.nvidia@gmail.com, reed@google.com

[jvanverth1, 2014-10-15 21:07:33]

jvanverth@google.com changed required reviewers:
+ reed@google.com

[reed1, 2014-10-15 21:17:57]

api part lgtm

[bungeman-skia, 2014-10-15 21:18:59]

On 2014/10/15 21:17:57, reed1 wrote:
> api part lgtm

lgtm

[jvanverth1, 2014-10-16 13:12:34]

The CQ bit was checked by jvanverth@google.com

[commit-bot: I haz the power, 2014-10-16 13:13:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/653133004/60001

[commit-bot: I haz the power, 2014-10-16 13:20:40]

Committed patchset #4 (id:60001) as 7851a56895c9c076f73a835a7dd51d3c6180c16f

[jvanverth1, 2014-10-16 15:04:06]

A revert of this CL (patchset #4 id:60001) has been created in
https://codereview.chromium.org/659993003/ by jvanverth@google.com.

The reason for reverting is: A large number of GMs on Ubuntu12 are failing. The
text layout on GPU is visibly different than that for 8888..