[SVGDom] Initial linear gradient support

experimental/svg/model/SkSVGHiddenContainer.h

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkSVGHiddenContainer_DEFINED
+#define SkSVGHiddenContainer_DEFINED
+
+#include "SkSVGContainer.h"
+
+class SkSVGHiddenContainer : public SkSVGContainer {
+public:
+    virtual ~SkSVGHiddenContainer() = default;
+
+protected:
+    explicit SkSVGHiddenContainer(SkSVGTag t) : INHERITED(t) {}
+
+    void onRender(const SkSVGRenderContext&) const final {}
+
+private:
+    typedef SkSVGContainer INHERITED;
+};
+
+#endif // SkSVGHiddenContainer_DEFINED