Add {Map,Set}::FromArray to the API

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index fb07e9ce8c68cdf94d29665cafa614b265b31b8f..0bc9d6453d476710776ba1d3ac954d479491a50b 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -2958,10 +2958,18 @@ class V8_EXPORT Map : public Object {
   Local<Array> AsArray() const;
 
   /**
-   * Creates a new Map.
+   * Creates a new empty Map.
    */
   static Local<Map> New(Isolate* isolate);
 
+  /**
+   * Creates a new Map containing the elements of array, which must be comprised
+   * of [key, value] arrays.
+   * Guaranteed to be side-effect free if the array contains no holes.
+   */
+  static V8_WARN_UNUSED_RESULT MaybeLocal<Map> FromArray(Local<Context> context,
+                                                         Local<Array> array);
+
   V8_INLINE static Map* Cast(Value* obj);
 
  private:
@@ -2983,10 +2991,17 @@ class V8_EXPORT Set : public Object {
   Local<Array> AsArray() const;
 
   /**
-   * Creates a new Set.
+   * Creates a new empty Set.
    */
   static Local<Set> New(Isolate* isolate);
 
+  /**
+   * Creates a new Set containing the items in array.
+   * Guaranteed to be side-effect free if the array contains no holes.
+   */
+  static V8_WARN_UNUSED_RESULT MaybeLocal<Set> FromArray(Local<Context> context,
+                                                         Local<Array> array);
+
   V8_INLINE static Set* Cast(Value* obj);
 
  private: