Revert of Implement approx-match support in image filter saveLayer() offscreen.

Revert of Implement approx-match support in image filter saveLayer() offscreen. (patchset #31 id:590001 of https://codereview.chromium.org/1034733002/)

Reason for revert:
Spoke to Stephen about this. Reverting because failing debug builds:

https://uberchromegw.corp.google.com/i/client.skia/builders/Test-Mac10.9-Clang-MacMini6.2-GPU-HD4000-x86_64-Debug/builds/51
https://uberchromegw.corp.google.com/i/client.skia/builders/Test-Ubuntu-GCC-ShuttleA-GPU-GTX660-x86_64-Debug/builds/54

Original issue's description:
> Implement approx-match support in image filter saveLayer() offscreen.
> 
> Currently, the GPU-side image filter implementation creates
> exact-match textures for the offscreen backing stores for
> saveLayer().  This is because several filters have GPU
> implementations which depend on the texture coordinates
> being 0..1.
> 
> The fix is three-fold:
> 
> 1) Store the actual requested size in the SkGpuDevice, so
> that when wrapping it in an SkBitmap for passing to 
> filterImage(), we can give it the original size.
> 2) Fix the filters (SkMagnifierImageFilter,
> SkLightingImageFilter, SkMatrixConvolutionImageFilter,
> SkMatrixImageFilter) whose GPU implementation depends on 
> 0..1 texture coordinates.
> 3) Remove the exception for GPU-side image filters in
> SkCanvas::internalSaveLayer().
> 
> For the lighting filters, there were two bugs which were 
> cancelling each other out: the sobel filter matrix was
> being computed upside down, but then we'd negate the 
> resulting normal. This worked fine in the exact-match case,
> but in the approx-match case we'd sample garbage along
> the edge pixels. Also, we never implemented the edge pixels
> according to spec in the GPU case. It requires a
> different fragment shader for each edge of the nine-patch,
> which meant we couldn't use asFragmentProcessor(), and had 
> to implement the drawing via a filterImageGPU() override. 
> In order to avoid polluting the public API, I inserted a 
> new base class, SkLightingImageFilterInternal above 
> Sk[Diffuse|Specular]LightingImageFilter to handle the 
> implementation.
> 
> For the SkMatrixConvolutionImageFilter, it seems the
> GLSL clamp() function occasionally returns values outside 
> the clamped range, resulting in access of garbage 
> texels even in GL_NEAREST. The fix here is to clamp to a
> rect inset by half a texel. There was also a bug in 
> the unpremultiply step when fConvolveAlpha is false.
> 
> For SkMatrixImageFilter, the fix was to make the generic
> draw path be more careful about when to use texture domain.
> If the bitmap already has a texture, use texture domain
> if the srcRect is smaller than the entire texture (not
> the entire bitmap).
> 
> N.B.: this change will cause some minor pixel diffs in the 
> GPU results of the following GMs (and possibly more):
> matriximagefilter, matrixconvolution, imagefiltersscaled,
> lighting, imagemagnifier, filterfastbounds,
> complexclip_aa_Layer_invert, complexclip_aa_layer,
> complexclip_bw_layer_invert, complexclip_bw_layer.
> 
> BUG=skia:3532
> 
> Committed: https://skia.googlesource.com/skia/+/b97dafefe63ea0a1bbce8e8b209f4920983fb8b9
> 
> Committed: https://skia.googlesource.com/skia/+/f5f8518fe0bbd2703e4ffc1b11ad7b4312ff7641
> 
> Committed: https://skia.googlesource.com/skia/+/46112cf2a7c7307f1c9eebb5f881cbda15aa460c

TBR=bsalomon@google.com,reed@chromium.org,senorblanco@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:3532
Committed: https://skia.googlesource.com/skia/+/82973dbf4f22928e8dd75c8bc5b155f842c8a557

[rmistry, 2015-04-01 22:52:49]

Created Revert of Implement approx-match support in image filter saveLayer()
offscreen.

[commit-bot: I haz the power, 2015-04-01 22:53:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1057693002/1

[commit-bot: I haz the power, 2015-04-01 22:53:16]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/82973dbf4f22928e8dd75c8bc5b155f842c8a557