Add isUnifiedMultisampled entry point to GrDrawContext

src/gpu/SkGpuDevice_drawTexture.cpp

Index: src/gpu/SkGpuDevice_drawTexture.cpp
diff --git a/src/gpu/SkGpuDevice_drawTexture.cpp b/src/gpu/SkGpuDevice_drawTexture.cpp
index 156bb7e6bfab4e05476d6d2af954d98caf16edb3..5eecf43e8338b6058d52edfa57b79b0268f635b8 100644
--- a/src/gpu/SkGpuDevice_drawTexture.cpp
+++ b/src/gpu/SkGpuDevice_drawTexture.cpp
@@ -186,7 +186,7 @@ void SkGpuDevice::drawTextureProducerImpl(GrTextureProducer* producer,
         SkMatrix combinedMatrix;
         combinedMatrix.setConcat(viewMatrix, srcToDstMatrix);
         if (can_ignore_bilerp_constraint(*producer, clippedSrcRect, combinedMatrix,
-                                         fRenderTarget->isUnifiedMultisampled())) {
+                                         fDrawContext->isUnifiedMultisampled())) {
             constraintMode = GrTextureAdjuster::kNo_FilterConstraint;
         }
     }