Expose Value::IsMap, IsSet, IsWeakMap, IsWeakSet in V8 API.

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index cb1294729c2a8c381c2625c3671ace5dd3a981b1..a9b7b8bb8793331113e715fffb4b4b63dbb3155f 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -1466,6 +1466,30 @@ class V8_EXPORT Value : public Data {
   bool IsPromise() const;
 
   /**
+   * Returns true if this value is a Map.
+   * This is an experimental feature.
+   */
+  bool IsMap() const;
+
+  /**
+   * Returns true if this value is a Set.
+   * This is an experimental feature.
+   */
+  bool IsSet() const;
+
+  /**
+   * Returns true if this value is a WeakMap.
+   * This is an experimental feature.
+   */
+  bool IsWeakMap() const;
+
+  /**
+   * Returns true if this value is a WeakSet.
+   * This is an experimental feature.
+   */
+  bool IsWeakSet() const;
+
+  /**
    * Returns true if this value is an ArrayBuffer.
    * This is an experimental feature.
    */