[WebGL-blink] Return meaningful information in WebGL context creation error message

public/platform/Platform.h

Index: public/platform/Platform.h
diff --git a/public/platform/Platform.h b/public/platform/Platform.h
index c319e30c3ab10f33258b52f0ef4015c0d13169d6..93daffdec5b6349aab73aa09160736d176386e50 100644
--- a/public/platform/Platform.h
+++ b/public/platform/Platform.h
@@ -558,6 +558,7 @@ public:
     // Returns newly allocated and initialized offscreen WebGraphicsContext3D instance.
     // Passing an existing context to shareContext will create the new context in the same share group as the passed context.
     virtual WebGraphicsContext3D* createOffscreenGraphicsContext3D(const WebGraphicsContext3D::Attributes&, WebGraphicsContext3D* shareContext) { return 0; }
+    virtual WebGraphicsContext3D* createOffscreenGraphicsContext3D(const WebGraphicsContext3D::Attributes&, WebGraphicsContext3D* shareContext, WebGLInfo* glInfo) { return 0; }
     virtual WebGraphicsContext3D* createOffscreenGraphicsContext3D(const WebGraphicsContext3D::Attributes&) { return 0; }
 
     // Returns a newly allocated and initialized offscreen context provider. The provider may return a null