1 files changed, 7 insertions, 9 deletions

diff --git a/js/src/jsfun.cpp b/js/src/jsfun.cpp
index 9d54fef780..65d44cba7a 100644
--- a/js/src/jsfun.cpp
+++ b/js/src/jsfun.cpp
@@ -523,7 +523,7 @@ js::XDRInterpretedFunction(XDRState<mode>* xdr, HandleScope enclosingScope,
 {
     enum FirstWordFlag {
         HasAtom             = 0x1,
-        IsStarGenerator     = 0x2,
+        HasStarGeneratorProto = 0x2,
         IsLazy              = 0x4,
         HasSingletonType    = 0x8
     };
@@ -552,8 +552,8 @@ js::XDRInterpretedFunction(XDRState<mode>* xdr, HandleScope enclosingScope,
         if (fun->explicitName() || fun->hasCompileTimeName() || fun->hasGuessedAtom())
             firstword |= HasAtom;
 
-        if (fun->isStarGenerator())
-            firstword |= IsStarGenerator;
+        if (fun->isStarGenerator() || fun->isAsync())
+            firstword |= HasStarGeneratorProto;
 
         if (fun->isInterpretedLazy()) {
             // Encode a lazy script.
@@ -589,7 +589,7 @@ js::XDRInterpretedFunction(XDRState<mode>* xdr, HandleScope enclosingScope,
 
     if (mode == XDR_DECODE) {
         RootedObject proto(cx);
-        if (firstword & IsStarGenerator) {
+        if (firstword & HasStarGeneratorProto) {
             proto = GlobalObject::getOrCreateStarGeneratorFunctionPrototype(cx, cx->global());
             if (!proto)
                 return false;
@@ -1596,8 +1596,6 @@ FunctionConstructor(JSContext* cx, const CallArgs& args, GeneratorKind generator
     bool isStarGenerator = generatorKind == StarGenerator;
     bool isAsync = asyncKind == AsyncFunction;
     MOZ_ASSERT(generatorKind != LegacyGenerator);
-    MOZ_ASSERT_IF(isAsync, isStarGenerator);
-    MOZ_ASSERT_IF(!isStarGenerator, !isAsync);
 
     RootedScript maybeScript(cx);
     const char* filename;
@@ -1709,7 +1707,7 @@ FunctionConstructor(JSContext* cx, const CallArgs& args, GeneratorKind generator
 
     // Step 4.d, use %Generator% as the fallback prototype.
     // Also use %Generator% for the unwrapped function of async functions.
-    if (!proto && isStarGenerator) {
+    if (!proto && (isStarGenerator || isAsync)) {
         proto = GlobalObject::getOrCreateStarGeneratorFunctionPrototype(cx, global);
         if (!proto)
             return false;
@@ -1777,7 +1775,7 @@ js::AsyncFunctionConstructor(JSContext* cx, unsigned argc, Value* vp)
     else
         newTarget = &args.callee();
 
-    if (!FunctionConstructor(cx, args, StarGenerator, AsyncFunction))
+    if (!FunctionConstructor(cx, args, NotGenerator, AsyncFunction))
         return false;
 
     // ES2017, draft rev 0f10dba4ad18de92d47d421f378233a2eae8f077
@@ -1973,7 +1971,7 @@ NewFunctionClone(JSContext* cx, HandleFunction fun, NewObjectKind newKind,
                  gc::AllocKind allocKind, HandleObject proto)
 {
     RootedObject cloneProto(cx, proto);
-    if (!proto && fun->isStarGenerator()) {
+    if (!proto && (fun->isStarGenerator() || fun->isAsync())) {
         cloneProto = GlobalObject::getOrCreateStarGeneratorFunctionPrototype(cx, cx->global());
         if (!cloneProto)
             return nullptr;