Move FP texture test buffers to heap.

Move FP texture test buffers to heap.

This is a speculative fix for the crashing N5 bots.  It looks like the bots are
always failing in or around FloatingPointTextureTest.

It looks like sometimes they're hitting a SIGBUS, which I suspect is stack
overflow.  FloatingPointTextureTest allocates ~320K on the stack, which may
be too much.  This CL moves those buffers to the heap.  For consistency I did
the same with the half-float tests, though they're only using ~1/8th the stack.

It looks like sometimes the bots are failing to malloc.  I don't understand that,
and this CL doesn't address that directly.  But it's possible this is still a stack
overflow, just trashing RAM and causing arbitrary mayhem instead of a SIGBUS.

I have no idea why this is a problem only on the N5.  I have been unable to
reproduce this locally, neither with a K N5 nor an L N5, but the bots are pretty
reliable.


NOTREECHECKS=true
BUG=skia:

Committed: https://skia.googlesource.com/skia/+/cada95ad9b8e6be9bdffe1a70968a2102cc3f09d

[mtklein_C, 2015-01-22 21:37:53]

mtklein@chromium.org changed reviewers:
+ jvanverth@google.com

[mtklein_C, 2015-01-22 21:37:56]

The CQ bit was checked by mtklein@chromium.org

[commit-bot: I haz the power, 2015-01-22 21:38:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/871623002/1

[commit-bot: I haz the power, 2015-01-22 21:38:33]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2015-01-23 03:38 UTC

[jvanverth1, 2015-01-22 21:44:01]

lgtm

[mtklein, 2015-01-22 21:50:12]

The CQ bit was unchecked by mtklein@google.com

[mtklein, 2015-01-22 21:50:21]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2015-01-22 21:50:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/871623002/1

[commit-bot: I haz the power, 2015-01-22 21:50:38]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/cada95ad9b8e6be9bdffe1a70968a2102cc3f09d