Add files

v8/include/cppgc/common.h

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+// Copyright 2020 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef INCLUDE_CPPGC_COMMON_H_
+#define INCLUDE_CPPGC_COMMON_H_
+
+#include "v8config.h"  // NOLINT(build/include_directory)
+
+namespace cppgc {
+
+/**
+ *  Indicator for the stack state of the embedder.
+ */
+enum class EmbedderStackState {
+  /**
+   * Stack may contain interesting heap pointers.
+   */
+  kMayContainHeapPointers,
+  /**
+   * Stack does not contain any interesting heap pointers.
+   */
+  kNoHeapPointers,
+};
+
+}  // namespace cppgc
+
+#endif  // INCLUDE_CPPGC_COMMON_H_