[async-iteration] implement Async-from-Sync Iterator

src/code-stub-assembler.cc

Index: src/code-stub-assembler.cc
diff --git a/src/code-stub-assembler.cc b/src/code-stub-assembler.cc
index 1c3359b982f4a77aa7c6068922c573b8e14022eb..e1ab040ab5f10425b6946375aa539df8ce965818 100644
--- a/src/code-stub-assembler.cc
+++ b/src/code-stub-assembler.cc
@@ -2890,6 +2890,11 @@ Node* CodeStubAssembler::IsJSReceiver(Node* object) {
   return IsJSReceiverInstanceType(LoadInstanceType(object));
 }
 
+Node* CodeStubAssembler::IsJSReceiverMap(Node* map) {
+  STATIC_ASSERT(LAST_JS_OBJECT_TYPE == LAST_TYPE);
+  return IsJSReceiverInstanceType(LoadMapInstanceType(map));
+}
+
 Node* CodeStubAssembler::IsJSObject(Node* object) {
   STATIC_ASSERT(LAST_JS_OBJECT_TYPE == LAST_TYPE);
   return Int32GreaterThanOrEqual(LoadInstanceType(object),