Add a GL cap for instanced rendering to floating point

include/gpu/GrTypes.h

Index: include/gpu/GrTypes.h
diff --git a/include/gpu/GrTypes.h b/include/gpu/GrTypes.h
index 979afb3b2fd7b5cd78d8c087cb7ea5d6be9d6ff7..a0f13aa6febcbf35f8909ac486e44d3eef5f5f5b 100644
--- a/include/gpu/GrTypes.h
+++ b/include/gpu/GrTypes.h
@@ -385,6 +385,17 @@ static inline bool GrPixelConfigIsAlphaOnly(GrPixelConfig config) {
     }
 }
 
+static inline bool GrPixelConfigIsFloatingPoint(GrPixelConfig config) {
+    switch (config) {
+        case kRGBA_float_GrPixelConfig:
+        case kAlpha_half_GrPixelConfig:
+        case kRGBA_half_GrPixelConfig:
+            return true;
+        default:
+            return false;
+    }
+}
+
 /**
  * Optional bitfield flags that can be set on GrSurfaceDesc (below).
  */