Reland "Remove ability to sample textures in vertex or geometry shaders."

This reverts commit 6e2625d9ae89f6709a606bcf1a15b35741393e02.

Reason for revert: Chrome fix has landed. This should work now.

Original change's description:
> Revert "Remove ability to sample textures in vertex or geometry shaders."
> 
> This reverts commit d50d6579d1c00de65b947c0531fa04c043729e49.
> 
> Reason for revert: chromes test gles test context is broken. Need to fix that then reland this
> 
> Original change's description:
> > Remove ability to sample textures in vertex or geometry shaders.
> > 
> > Bug: skia:
> > Change-Id: I69cd07a4bbe4879e855fb4aa6289a049adf4e059
> > Reviewed-on: https://skia-review.googlesource.com/c/160021
> > Commit-Queue: Greg Daniel <egdaniel@google.com>
> > Reviewed-by: Chris Dalton <csmartdalton@google.com>
> 
> TBR=egdaniel@google.com,bsalomon@google.com,csmartdalton@google.com
> 
> Change-Id: I309dfa5f7118cb8d7280aaf6a88e1df232bd7099
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: skia:
> Reviewed-on: https://skia-review.googlesource.com/c/160163
> Reviewed-by: Greg Daniel <egdaniel@google.com>
> Commit-Queue: Greg Daniel <egdaniel@google.com>

TBR=egdaniel@google.com,bsalomon@google.com,csmartdalton@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: skia:
Change-Id: Id2b5bdf883dbd0236f847649a30d15a492ab481e
Reviewed-on: https://skia-review.googlesource.com/c/160461
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
diff --git a/src/gpu/gl/GrGLUniformHandler.cpp b/src/gpu/gl/GrGLUniformHandler.cpp
index 0d57a14..7551e9a 100644
--- a/src/gpu/gl/GrGLUniformHandler.cpp
+++ b/src/gpu/gl/GrGLUniformHandler.cpp
@@ -61,13 +61,11 @@
     return GrGLSLUniformHandler::UniformHandle(fUniforms.count() - 1);
 }
 
-GrGLSLUniformHandler::SamplerHandle GrGLUniformHandler::addSampler(uint32_t visibility,
-                                                                   GrSwizzle swizzle,
+GrGLSLUniformHandler::SamplerHandle GrGLUniformHandler::addSampler(GrSwizzle swizzle,
                                                                    GrTextureType type,
                                                                    GrSLPrecision precision,
                                                                    const char* name) {
     SkASSERT(name && strlen(name));
-    SkASSERT(0 != visibility);
 
     SkString mangleName;
     char prefix = 'u';
@@ -79,7 +77,7 @@
     sampler.fVariable.setPrecision(precision);
     sampler.fVariable.setName(mangleName);
     sampler.fLocation = -1;
-    sampler.fVisibility = visibility;
+    sampler.fVisibility = kFragment_GrShaderFlag;
     fSamplerSwizzles.push_back(swizzle);
     SkASSERT(fSamplers.count() == fSamplerSwizzles.count());
     return GrGLSLUniformHandler::SamplerHandle(fSamplers.count() - 1);