apply mozilla patch for skbug.com/4547

include/gpu/GrGpuResourceRef.h

Index: include/gpu/GrGpuResourceRef.h
diff --git a/include/gpu/GrGpuResourceRef.h b/include/gpu/GrGpuResourceRef.h
index 70d25687846252e38aaec0eba6a9b171e85b9f09..4511adce6823523a69e25d3fd25233285dff66d6 100644
--- a/include/gpu/GrGpuResourceRef.h
+++ b/include/gpu/GrGpuResourceRef.h
@@ -182,7 +182,11 @@ public:
         this->release();
     }
 
-    operator bool() const { return SkToBool(fResource); }
+    explicit operator bool() const { return SkToBool(fResource); }

[bungeman-skia, 2015/11/10 17:20:01]

Explicit operator bool has issues in VS2013, which is why we're still avoiding
it. We need to be really careful with this.

+
+    bool operator==(const GrPendingIOResource& other) const {
+        return fResource == other.fResource;
+    }
 
     T* get() const { return fResource; }