[ignition] desugar GetIterator() via bytecode rather than via AST

src/interpreter/bytecode-generator.cc

Index: src/interpreter/bytecode-generator.cc
diff --git a/src/interpreter/bytecode-generator.cc b/src/interpreter/bytecode-generator.cc
index 13351845de104a06bd8cf275beb2ea1631db2d70..9469fb58b8b657f7369dde57e3a5b06e070a5752 100644
--- a/src/interpreter/bytecode-generator.cc
+++ b/src/interpreter/bytecode-generator.cc
@@ -583,6 +583,7 @@ BytecodeGenerator::BytecodeGenerator(CompilationInfo* info)
       generator_state_(),
       loop_depth_(0),
       home_object_symbol_(info->isolate()->factory()->home_object_symbol()),
+      iterator_symbol_(info->isolate()->factory()->iterator_symbol()),
       empty_fixed_array_(info->isolate()->factory()->empty_fixed_array()) {
   AstValueFactory* ast_value_factory = info->parse_info()->ast_value_factory();
   const AstRawString* prototype_string = ast_value_factory->prototype_string();
@@ -2852,6 +2853,33 @@ void BytecodeGenerator::VisitEmptyParentheses(EmptyParentheses* expr) {
   UNREACHABLE();
 }
 
+void BytecodeGenerator::VisitGetIterator(GetIterator* expr) {
+  FeedbackVectorSlot load_slot = expr->IteratorPropertyFeedbackSlot();
+  FeedbackVectorSlot call_slot = expr->IteratorCallFeedbackSlot();
+
+  RegisterList args = register_allocator()->NewRegisterList(1);
+  Register method = register_allocator()->NewRegister();
+  Register obj = args[0];
+
+  VisitForAccumulatorValue(expr->iterable());
+
+  // Let method be GetMethod(obj, @@iterator).
+  builder()
+      ->StoreAccumulatorInRegister(obj)
+      .LoadNamedProperty(obj, iterator_symbol(), feedback_index(load_slot))
+      .StoreAccumulatorInRegister(method);
+
+  // Let iterator be Call(method, obj).
+  builder()->Call(method, args, feedback_index(call_slot),
+                  Call::NAMED_PROPERTY_CALL);
+
+  // If Type(iterator) is not Object, throw a TypeError exception.
+  BytecodeLabel no_type_error;
+  builder()->JumpIfJSReceiver(&no_type_error);
+  builder()->CallRuntime(Runtime::kThrowSymbolIteratorInvalid);
+  builder()->Bind(&no_type_error);
+}
+
 void BytecodeGenerator::VisitThisFunction(ThisFunction* expr) {
   builder()->LoadAccumulatorWithRegister(Register::function_closure());
 }