Revert of Makes GrGLProgramDesc's key store the lengths as well as offsets of the effect keys.

Revert of Makes GrGLProgramDesc's key store the lengths as well as offsets of the effect keys. (https://codereview.chromium.org/379113004/)

Reason for revert:
Most likely candidate for Valgrind failures:

[21:10:08.755668] ==3036== Use of uninitialised value of size 8
[21:10:08.755753] ==3036==    at 0x734AB2: GrGpuGL::ProgramCache::getProgram(GrGLProgramDesc const&, GrEffectStage const**, GrEffectStage const**) (GrGpuGL_program.cpp:107)
[21:10:08.755788] ==3036==    by 0x734ED2: GrGpuGL::flushGraphicsState(GrGpu::DrawType, GrDeviceCoordTexture const*) (GrGpuGL_program.cpp:253)
[21:10:08.755811] ==3036==    by 0x6E81C2: GrGpu::setupClipAndFlushState(GrGpu::DrawType, GrDeviceCoordTexture const*, GrDrawState::AutoRestoreEffects*, SkRect const*) (GrGpu.cpp:350)
[21:10:08.755837] ==3036==    by 0x6E9BE8: GrGpu::onDraw(GrDrawTarget::DrawInfo const&) (GrGpu.cpp:390)
[21:10:08.755858] ==3036==    by 0x6EEECE: GrInOrderDrawBuffer::flush() (GrDrawTarget.h:506)
[21:10:08.755879] ==3036==    by 0x6D0EB4: GrContext::flush(int) (GrContext.cpp:1327)
[21:10:08.755900] ==3036==    by 0x6D3F8F: GrContext::writeTexturePixels(GrTexture*, int, int, int, int, GrPixelConfig, void const*, unsigned long, unsigned int) (GrContext.cpp:1349)
[21:10:08.755922] ==3036==    by 0x6D39D7: GrContext::writeRenderTargetPixels(GrRenderTarget*, int, int, int, int, GrPixelConfig, void const*, unsigned long, unsigned int) (GrContext.cpp:1632)
[21:10:08.755949] ==3036==    by 0x6FFDF3: GrRenderTarget::writePixels(int, int, int, int, GrPixelConfig, void const*, unsigned long, unsigned int) (GrRenderTarget.cpp:45)
[21:10:08.755978] ==3036==    by 0x735563: SkGpuDevice::onWritePixels(SkImageInfo const&, void const*, unsigned long, int, int) (SkGpuDevice.cpp:280)
[21:10:08.756003] ==3036==    by 0x57A048: SkBaseDevice::writePixels(SkImageInfo const&, void const*, unsigned long, int, int) (SkDevice.cpp:106)
[21:10:08.756025] ==3036==    by 0x56D0AE: SkCanvas::writePixels(SkImageInfo const&, void const*, unsigned long, int, int) (SkCanvas.cpp:700)
[21:10:08.756050] ==3036==    by 0x56D156: SkCanvas::writePixels(SkBitmap const&, int, int) (SkCanvas.cpp:652)
[21:10:08.756077] ==3036==    by 0x5109B6: test_WritePixels(skiatest::Reporter*, GrContextFactory*) (WritePixelsTest.cpp:464)
[21:10:08.756099] ==3036==    by 0x51114C: skiatest::WritePixelsClass::onRun(skiatest::Reporter*) (WritePixelsTest.cpp:361)
[21:10:08.756122] ==3036==    by 0x406BE8: skiatest::Test::run() (Test.cpp:107)
[21:10:08.756145] ==3036==    by 0x4064C2: SkTestRunnable::run() (skia_test.cpp:109)
[21:10:08.756167] ==3036==    by 0x405D1A: tool_main(int, char**) (skia_test.cpp:221)
[21:10:08.756189] ==3036==    by 0x405F75: main (skia_test.cpp:239)
[21:10:08.756211] ==3036==  Uninitialised value was created by a stack allocation
[21:10:08.756233] ==3036==    at 0x734CC8: GrGpuGL::flushGraphicsState(GrGpu::DrawType, GrDeviceCoordTexture const*) (GrGpuGL_program.cpp:213)


Original issue's description:
> Makes GrGLProgramDesc's key store the lengths as well as offsets of the effect keys.
> 
> Makes it possible to use GrBackendEffectFactories other than GrTBEF by moving meta-key generation out of GrTBEF.
> 
> Cleans up docs around GrBackendEffectFactory.
> 
> Committed: https://skia.googlesource.com/skia/+/c0ea398aff8254e31152cbb94c9ab6150428e252

TBR=robertphillips@google.com,jvanverth@google.com,bsalomon@google.com
NOTREECHECKS=true
NOTRY=true

Committed: https://skia.googlesource.com/skia/+/7940100faec0b758645d40c876e9c796884410f7

[mtklein, 2014-07-16 13:16:18]

Created Revert of Makes GrGLProgramDesc's key store the lengths as well as
offsets of the effect keys.

[commit-bot: I haz the power, 2014-07-16 13:16:36]

CQ is trying da patch. Follow status at
 https://skia-tree-status.appspot.com/cq/mtklein@google.com/394213002/1

[commit-bot: I haz the power, 2014-07-16 13:16:48]

Change committed as 7940100faec0b758645d40c876e9c796884410f7