Deparameterize SkVarAlloc.

Deparameterize SkVarAlloc.

SkRecord performance is not sensitive to these values, so we can cut some
storage.  This rearranges the space-remaining logic to use a count of bytes
left rather than a pointer to the end, cutting memory usage a little more.

An SkVarAlloc used to weigh 20 or 32 bytes which now becomes 16 or 24.

I think if I think about it a bit more I can trim off that Block* too,
getting us to 12 or 16 bytes.

Because we now just always grow by doubling, this CL switches from storing
fSmallest to its log base 2.  This has the nice effect of never having to worry
about it overflowing, and means we can probably squeeze it down into a byte
if we want, even 6 bits.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/bc415389855888af5a1282ca4b6bee30afa3d69d

CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu12-ShuttleA-GTX660-x86-Debug-Trybot

Committed: https://skia.googlesource.com/skia/+/f2950b1c4538fa638a594af6beacd3d1434eb74d

[mtklein, 2014-11-13 18:29:33]

mtklein@google.com changed reviewers:
+ mtklein@google.com, reed@google.com

[mtklein, 2014-11-13 18:29:50]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2014-11-13 18:30:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/721313002/100001

[commit-bot: I haz the power, 2014-11-13 18:30:12]

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 2014-11-14 00:30 UTC

[reed1, 2014-11-13 18:50:29]

lgtm

[commit-bot: I haz the power, 2014-11-13 18:51:44]

Committed patchset #6 (id:100001) as
https://skia.googlesource.com/skia/+/bc415389855888af5a1282ca4b6bee30afa3d69d

[mtklein, 2014-11-13 19:22:30]

A revert of this CL (patchset #6 id:100001) has been created in
https://codereview.chromium.org/718203006/ by mtklein@google.com.

The reason for reverting is: Unit test failures on 32-bit machines.

test Record_Alignment:
../../tests/RecordTest.cpp:100	is_aligned(record.alloc<uint64_t>()).

[mtklein, 2014-11-13 19:57:50]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2014-11-13 19:59:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/721313002/120001

[commit-bot: I haz the power, 2014-11-13 20:41:21]

Committed patchset #7 (id:120001) as
https://skia.googlesource.com/skia/+/f2950b1c4538fa638a594af6beacd3d1434eb74d