WIP [esnext] implement async iteration proposal

src/compiler/js-intrinsic-lowering.cc

Index: src/compiler/js-intrinsic-lowering.cc
diff --git a/src/compiler/js-intrinsic-lowering.cc b/src/compiler/js-intrinsic-lowering.cc
index 9a1fe0a8b6fa4e4e12b8dde28101c1b96cc40b92..28e4c27db5af5675d85bf59dc1eb2fa5b7bd128b 100644
--- a/src/compiler/js-intrinsic-lowering.cc
+++ b/src/compiler/js-intrinsic-lowering.cc
@@ -40,6 +40,8 @@ Reduction JSIntrinsicLowering::Reduce(Node* node) {
       return ReduceGeneratorClose(node);
     case Runtime::kInlineGeneratorGetInputOrDebugPos:
       return ReduceGeneratorGetInputOrDebugPos(node);
+    case Runtime::kInlineAsyncGeneratorGetAwaitInput:
+      return ReduceAsyncGeneratorGetAwaitInput(node);
     case Runtime::kInlineGeneratorGetResumeMode:
       return ReduceGeneratorGetResumeMode(node);
     case Runtime::kInlineIsArray:
@@ -140,6 +142,31 @@ Reduction JSIntrinsicLowering::ReduceGeneratorGetInputOrDebugPos(Node* node) {
   return Change(node, op, generator, effect, control);
 }
 
+Reduction JSIntrinsicLowering::ReduceAsyncGeneratorGetAwaitInput(Node* node) {
+  Node* const generator = NodeProperties::GetValueInput(node, 0);
+  Node* const effect = NodeProperties::GetEffectInput(node);
+  Node* const control = NodeProperties::GetControlInput(node);
+  Operator const* const op = simplified()->LoadField(
+      AccessBuilder::ForJSAsyncGeneratorObjectAwaitInput());
+
+  return Change(node, op, generator, effect, control);
+}
+
+Reduction JSIntrinsicLowering::ReduceGeneratorSaveInputForAwait(Node* node) {
+  Node* const generator = NodeProperties::GetValueInput(node, 0);
+  Node* const effect = NodeProperties::GetEffectInput(node);
+  Node* const control = NodeProperties::GetControlInput(node);
+
+  Node* const input = graph()->NewNode(
+      simplified()->LoadField(
+          AccessBuilder::ForJSAsyncGeneratorObjectAwaitInput()),
+      generator, effect, control);
+
+  Operator const* const op = simplified()->StoreField(
+      AccessBuilder::ForJSGeneratorObjectContinuation());
+  return Change(node, op, generator, input, effect, control);
+}
+
 Reduction JSIntrinsicLowering::ReduceGeneratorGetResumeMode(Node* node) {
   Node* const generator = NodeProperties::GetValueInput(node, 0);
   Node* const effect = NodeProperties::GetEffectInput(node);