Revert of Calculate inverse scale for distance fields in vertex shader

Revert of Calculate inverse scale for distance fields in vertex shader (patchset #6 id:100001 of https://codereview.chromium.org/1029423003/)

Reason for revert:
This appears to be breaking large text on Nexus 7.

Original issue's description:
> Calculate inverse scale for distance field text in vertex shader
> 
> This is for the uniform scale case only. Using the dFdx() function on certain
> Mali GPUs causes issues because the precision is too low, so we have to
> compute 1/scale from the view matrix instead.
> 
> BUG=skia:3528
> 
> Committed: https://skia.googlesource.com/skia/+/5b143038cb47763974d2750ed78d436eb6c38bea

TBR=bsalomon@google.com,joshualitt@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:3528
Committed: https://skia.googlesource.com/skia/+/ff271c29a64f59d538e644210b0f207666f856b5

[jvanverth1, 2015-04-06 20:58:39]

Created Revert of Calculate inverse scale for distance fields in vertex shader

[commit-bot: I haz the power, 2015-04-06 20:58:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1066613003/1

[commit-bot: I haz the power, 2015-04-06 20:59:02]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/ff271c29a64f59d538e644210b0f207666f856b5