Revert of Use unorm shorts for texture coordinates when rendering text. (patchset #3 id:40001 of https://codereview.chromium.org/1713693002/ )

Reason for revert:
Causing issues with text on Mali 400s. Examples: 	largeglyphblur, imageblurtiled. It appears that there are precision problems.

Original issue's description:
> Use unorm shorts for texture coordinates when rendering text.
>
> There are a couple of reasons for this:
> - Vulkan does not guarantee conversions from integral vertex attributes
>   to floating point shader variables
> - This may be faster and more precise on some platforms, as it avoids
>   the aforementioned conversion and changes a multiply by a very small
>   value to a multiply by a medium-sized value.
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1713693002
> TBR=bsalomon@google.com
>
> Committed: https://skia.googlesource.com/skia/+/e507ff0460f4f878214b9454fb5b9ab8d64d8063

TBR=joshualitt@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1709133003
diff --git a/src/gpu/effects/GrDistanceFieldGeoProc.cpp b/src/gpu/effects/GrDistanceFieldGeoProc.cpp
index dc01b62..50e78cc 100644
--- a/src/gpu/effects/GrDistanceFieldGeoProc.cpp
+++ b/src/gpu/effects/GrDistanceFieldGeoProc.cpp
@@ -78,20 +78,23 @@
 
         // add varyings
         GrGLSLVertToFrag recipScale(kFloat_GrSLType);
-        GrGLSLVertToFrag uv(kVec2f_GrSLType);
+        GrGLSLVertToFrag st(kVec2f_GrSLType);
         bool isSimilarity = SkToBool(dfTexEffect.getFlags() & kSimilarity_DistanceFieldEffectFlag);
-        varyingHandler->addVarying("TextureCoords", &uv, kHigh_GrSLPrecision);
-        vertBuilder->codeAppendf("%s = %s;", uv.vsOut(), dfTexEffect.inTextureCoords()->fName);
+        varyingHandler->addVarying("IntTextureCoords", &st, kHigh_GrSLPrecision);
+        vertBuilder->codeAppendf("%s = %s;", st.vsOut(), dfTexEffect.inTextureCoords()->fName);
 
         // compute numbers to be hardcoded to convert texture coordinates from int to float
         SkASSERT(dfTexEffect.numTextures() == 1);
         GrTexture* atlas = dfTexEffect.textureAccess(0).getTexture();
         SkASSERT(atlas && SkIsPow2(atlas->width()) && SkIsPow2(atlas->height()));
+        SkScalar recipWidth = 1.0f / atlas->width();
+        SkScalar recipHeight = 1.0f / atlas->height();
 
-        GrGLSLVertToFrag st(kVec2f_GrSLType);
-        varyingHandler->addVarying("IntTextureCoords", &st, kHigh_GrSLPrecision);
-        vertBuilder->codeAppendf("%s = vec2(%d, %d) * %s;", st.vsOut(),
-                                 atlas->width(), atlas->height(),
+        GrGLSLVertToFrag uv(kVec2f_GrSLType);
+        varyingHandler->addVarying("TextureCoords", &uv, kHigh_GrSLPrecision);
+        vertBuilder->codeAppendf("%s = vec2(%.*f, %.*f) * %s;", uv.vsOut(),
+                                 GR_SIGNIFICANT_POW2_DECIMAL_DIG, recipWidth,
+                                 GR_SIGNIFICANT_POW2_DECIMAL_DIG, recipHeight,
                                  dfTexEffect.inTextureCoords()->fName);
         
         // Use highp to work around aliasing issues
@@ -221,7 +224,7 @@
                                                    kHigh_GrSLPrecision));
     fInColor = &this->addVertexAttrib(Attribute("inColor", kVec4ub_GrVertexAttribType));
     fInTextureCoords = &this->addVertexAttrib(Attribute("inTextureCoords",
-                                                          kVec2us_GrVertexAttribType));
+                                                          kVec2s_GrVertexAttribType));
     this->addTextureAccess(&fTextureAccess);
 }
 
@@ -519,19 +522,22 @@
         // set up varyings
         bool isUniformScale = SkToBool(dfTexEffect.getFlags() & kUniformScale_DistanceFieldEffectMask);
         GrGLSLVertToFrag recipScale(kFloat_GrSLType);
-        GrGLSLVertToFrag uv(kVec2f_GrSLType);
-        varyingHandler->addVarying("TextureCoords", &uv, kHigh_GrSLPrecision);
-        vertBuilder->codeAppendf("%s = %s;", uv.vsOut(), dfTexEffect.inTextureCoords()->fName);
+        GrGLSLVertToFrag st(kVec2f_GrSLType);
+        varyingHandler->addVarying("IntTextureCoords", &st, kHigh_GrSLPrecision);
+        vertBuilder->codeAppendf("%s = %s;", st.vsOut(), dfTexEffect.inTextureCoords()->fName);
 
         // compute numbers to be hardcoded to convert texture coordinates from int to float
         SkASSERT(dfTexEffect.numTextures() == 1);
         GrTexture* atlas = dfTexEffect.textureAccess(0).getTexture();
         SkASSERT(atlas && SkIsPow2(atlas->width()) && SkIsPow2(atlas->height()));
+        SkScalar recipWidth = 1.0f / atlas->width();
+        SkScalar recipHeight = 1.0f / atlas->height();
 
-        GrGLSLVertToFrag st(kVec2f_GrSLType);
-        varyingHandler->addVarying("IntTextureCoords", &st, kHigh_GrSLPrecision);
-        vertBuilder->codeAppendf("%s = vec2(%d, %d) * %s;", st.vsOut(),
-                                 atlas->width(), atlas->height(),
+        GrGLSLVertToFrag uv(kVec2f_GrSLType);
+        varyingHandler->addVarying("TextureCoords", &uv, kHigh_GrSLPrecision);
+        vertBuilder->codeAppendf("%s = vec2(%.*f, %.*f) * %s;", uv.vsOut(),
+                                 GR_SIGNIFICANT_POW2_DECIMAL_DIG, recipWidth,
+                                 GR_SIGNIFICANT_POW2_DECIMAL_DIG, recipHeight,
                                  dfTexEffect.inTextureCoords()->fName);
 
         // add frag shader code
@@ -702,7 +708,7 @@
                                                    kHigh_GrSLPrecision));
     fInColor = &this->addVertexAttrib(Attribute("inColor", kVec4ub_GrVertexAttribType));
     fInTextureCoords = &this->addVertexAttrib(Attribute("inTextureCoords",
-                                                        kVec2us_GrVertexAttribType));
+                                                        kVec2s_GrVertexAttribType));
     this->addTextureAccess(&fTextureAccess);
 }