[esnext] prototype runtime implementation for async functions

src/globals.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_GLOBALS_H_
 #define V8_GLOBALS_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 1040 matching lines @@
   DCHECK(IsValidFunctionKind(kind));
   return kind & FunctionKind::kClassConstructor;
 }
 
 
 inline bool IsConstructable(FunctionKind kind, LanguageMode mode) {
   if (IsAccessorFunction(kind)) return false;
   if (IsConciseMethod(kind)) return false;
   if (IsArrowFunction(kind)) return false;
   if (IsGeneratorFunction(kind)) return false;
+  if (IsAsyncFunction(kind)) return false;
   return true;
 }
 
 
 inline uint32_t ObjectHash(Address address) {
   // All objects are at least pointer aligned, so we can remove the trailing
   // zeros.
   return static_cast<uint32_t>(bit_cast<uintptr_t>(address) >>
                                kPointerSizeLog2);
 }
 
 }  // namespace internal
 }  // namespace v8
 
 namespace i = v8::internal;
 
 #endif  // V8_GLOBALS_H_