Revert "Reland "Remove use of integers for atlas indexing""

This reverts commit 3ae2cd5ef8906947ee9189299f6f08af07bea8c2.

Reason for revert: Odd issues with fontcache-mt on Vulkan.

Original change's description:
> Reland "Remove use of integers for atlas indexing"
> 
> This is a reland of 3a8f345cf5689c6e1f22e852acfde4b8b1e5ba42
> 
> Original change's description:
> > Remove use of integers for atlas indexing
> > 
> > Bug: skia:
> > Change-Id: I7c29e90de6531a35c415f0338e23c176a7293040
> > Reviewed-on: https://skia-review.googlesource.com/c/171233
> > Reviewed-by: Brian Salomon <bsalomon@google.com>
> > Commit-Queue: Jim Van Verth <jvanverth@google.com>
> 
> Bug: skia:
> Change-Id: Ifb041f74028a119ba410e80cbfaedce34614f90b
> Reviewed-on: https://skia-review.googlesource.com/c/171539
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Jim Van Verth <jvanverth@google.com>

TBR=jvanverth@google.com,bsalomon@google.com

Change-Id: I82fb5073d11b52e35b6f731415e2a87f62bc8edb
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/c/171780
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
diff --git a/src/gpu/effects/GrBitmapTextGeoProc.cpp b/src/gpu/effects/GrBitmapTextGeoProc.cpp
index 00743b1..c59ae4a 100644
--- a/src/gpu/effects/GrBitmapTextGeoProc.cpp
+++ b/src/gpu/effects/GrBitmapTextGeoProc.cpp
@@ -40,7 +40,8 @@
                                                           &atlasSizeInvName);
 
         GrGLSLVarying uv(kFloat2_GrSLType);
-        GrGLSLVarying texIdx(kFloat_GrSLType);
+        GrSLType texIdxType = args.fShaderCaps->integerSupport() ? kInt_GrSLType : kFloat_GrSLType;
+        GrGLSLVarying texIdx(texIdxType);
         append_index_uv_varyings(args, btgp.inTextureCoords().name(), atlasSizeInvName, &uv,
                                  &texIdx, nullptr);
 
@@ -143,8 +144,8 @@
         fInColor = {"inColor", kUByte4_norm_GrVertexAttribType, kHalf4_GrSLType};
     }
 
-    fInTextureCoords = { "inTextureCoords", kUShort2_GrVertexAttribType,
-                         caps.integerSupport() ? kUShort2_GrSLType : kFloat2_GrSLType };
+    fInTextureCoords = {"inTextureCoords", kUShort2_GrVertexAttribType,
+                        caps.integerSupport() ? kUShort2_GrSLType : kFloat2_GrSLType};
     this->setVertexAttributes(&fInPosition, 3);
 
     if (numActiveProxies) {