Add explicit conversion from uint2 to float2 for Vulkan

Change-Id: I07a28c77f3c9b87d6713ae1d6b7e7d1285098aa8
Reviewed-on: https://skia-review.googlesource.com/38728
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/effects/GrBitmapTextGeoProc.cpp b/src/gpu/effects/GrBitmapTextGeoProc.cpp
index d24ddf8..d87f7c0 100644
--- a/src/gpu/effects/GrBitmapTextGeoProc.cpp
+++ b/src/gpu/effects/GrBitmapTextGeoProc.cpp
@@ -38,7 +38,8 @@
 
         GrGLSLVertToFrag v(kVec2f_GrSLType);
         varyingHandler->addVarying("TextureCoords", &v, kHigh_GrSLPrecision);
-        vertBuilder->codeAppendf("%s = %s * %s;", v.vsOut(),
+        vertBuilder->codeAppendf("%s = float2(%s.x, %s.y) * %s;", v.vsOut(),
+                                 btgp.inTextureCoords()->fName,
                                  btgp.inTextureCoords()->fName,
                                  atlasSizeInvName);