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

src/compiler/ast-graph-builder.cc

Index: src/compiler/ast-graph-builder.cc
diff --git a/src/compiler/ast-graph-builder.cc b/src/compiler/ast-graph-builder.cc
index 43e229221e03c6bf8496de377396fdfc4f8cb65c..ff11d9b7ebdcfc6f6943c0627a6d8569c8f64dc2 100644
--- a/src/compiler/ast-graph-builder.cc
+++ b/src/compiler/ast-graph-builder.cc
@@ -2165,6 +2165,10 @@ void AstGraphBuilder::VisitEmptyParentheses(EmptyParentheses* expr) {
   UNREACHABLE();
 }
 
+void AstGraphBuilder::VisitGetIterator(GetIterator* expr) {
+  // GetIterator is supported only by going through Ignition first.
+  UNREACHABLE();
+}
 
 void AstGraphBuilder::VisitThisFunction(ThisFunction* expr) {
   Node* value = GetFunctionClosure();