1 files changed, 23 insertions, 0 deletions
diff --git a/js/src/builtin/Utilities.js b/js/src/builtin/Utilities.js
index bfb1fe7f4..2dece3801 100644
--- a/js/src/builtin/Utilities.js
+++ b/js/src/builtin/Utilities.js
@@ -154,6 +154,29 @@ function GetIterator(obj, method) {
     return iterator;
 }
 
+// ES2017 draft rev 7.4.6.
+// When completion.[[Type]] is throw.
+function IteratorCloseThrow(iter) {
+    // Steps 1-2 (implicit)
+
+    // Step 3.
+    var returnMethod = GetMethod(iter, "return");
+
+    // Step 4 (done in caller).
+    if (returnMethod === undefined)
+        return;
+
+    try {
+        // Step 5.
+        callContentFunction(returnMethod, iter);
+    } catch (e) {
+    }
+
+    // Step 6 (done in caller).
+
+    // Steps 7-9 (skipped).
+}
+
 var _builtinCtorsCache = {__proto__: null};
 
 function GetBuiltinConstructor(builtinName) {