Workaround for PowerVR clear issue.

src/gpu/GrDrawTargetCaps.h

Index: src/gpu/GrDrawTargetCaps.h
diff --git a/src/gpu/GrDrawTargetCaps.h b/src/gpu/GrDrawTargetCaps.h
index e468bc41ab39cf62b1c678b6ce65dd6ae6f15fb9..f13aa53c806dfe8173174ddfa901108b58bc00d9 100644
--- a/src/gpu/GrDrawTargetCaps.h
+++ b/src/gpu/GrDrawTargetCaps.h
@@ -46,6 +46,8 @@ public:
     bool gpuTracingSupport() const { return fGpuTracingSupport; }
     bool compressedTexSubImageSupport() const { return fCompressedTexSubImageSupport; }
 
+    bool useDrawInsteadOfClear() const { return fUseDrawInsteadOfClear; }
+
     /**
      * Indicates whether GPU->CPU memory mapping for GPU resources such as vertex buffers and
      * textures allows partial mappings or full mappings.
@@ -104,6 +106,9 @@ protected:
     bool fGpuTracingSupport         : 1;
     bool fCompressedTexSubImageSupport : 1;
 
+    // Driver workaround
+    bool fUseDrawInsteadOfClear     : 1;
+
     uint32_t fMapBufferFlags;
 
     int fMaxRenderTargetSize;