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

src/code-stub-assembler.h

 // Copyright 2016 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_CODE_STUB_ASSEMBLER_H_
 #define V8_CODE_STUB_ASSEMBLER_H_
 
 #include <functional>
 
 #include "src/compiler/code-assembler.h"
@@ skipping 1220 matching lines @@
   Node* AllocatePromiseReactionJobInfo(Node* value, Node* tasks,
                                        Node* deferred_promise,
                                        Node* deferred_on_resolve,
                                        Node* deferred_on_reject, Node* context);
 
   // Support for printf-style debugging
   void Print(const char* s);
   void Print(const char* prefix, Node* tagged_value);
   inline void Print(Node* tagged_value) { return Print(nullptr, tagged_value); }
 
+  template <class... TArgs>
+  Node* MakeTypeError(MessageTemplate::Template message, Node* context,
+                      TArgs... args) {
+    Node* const make_type_error = LoadContextElement(
+        LoadNativeContext(context), Context::MAKE_TYPE_ERROR_INDEX);
+    return CallJS(CodeFactory::Call(isolate()), context, make_type_error,

[caitp, 2017/02/15 22:18:01]

Maybe it would make sense for MakeTypeError (and friends) to be a runtime
function instead of a C++ builtin. At least it would avoid needing to load it
from native_context, and avoid installing it per context. Would make the CSA
helper simpler

+                  UndefinedConstant(), SmiConstant(message), args...);
+  }
+
  protected:
   void DescriptorLookup(Node* unique_name, Node* descriptors, Node* bitfield3,
                         Label* if_found, Variable* var_name_index,
                         Label* if_not_found);
   void DescriptorLookupLinear(Node* unique_name, Node* descriptors, Node* nof,
                               Label* if_found, Variable* var_name_index,
                               Label* if_not_found);
   void DescriptorLookupBinary(Node* unique_name, Node* descriptors, Node* nof,
                               Label* if_found, Variable* var_name_index,
                               Label* if_not_found);
@@ skipping 133 matching lines @@
   }
 #else
 #define CSA_SLOW_ASSERT(csa, x) ((void)0)
 #endif
 
 DEFINE_OPERATORS_FOR_FLAGS(CodeStubAssembler::AllocationFlags);
 
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_CODE_STUB_ASSEMBLER_H_