Cleanup access to guarded_fields

runtime/vm/compiler.cc

Index: runtime/vm/compiler.cc
diff --git a/runtime/vm/compiler.cc b/runtime/vm/compiler.cc
index 0578d0ea61883b71158c73a3e30d0773a806c07f..fcab75e3fefb12fe47cbdf506932f92cfbc41682 100644
--- a/runtime/vm/compiler.cc
+++ b/runtime/vm/compiler.cc
@@ -489,7 +489,7 @@ void CompileParsedFunctionHelper::FinalizeCompilation(
           }
         }
       }
-      if (!flow_graph->guarded_fields()->is_empty()) {
+      if (!flow_graph->parsed_function().guarded_fields()->is_empty()) {
         if (field_invalidation_gen_at_start() !=
             isolate()->field_invalidation_gen()) {
           code_is_valid = false;
@@ -526,10 +526,10 @@ void CompileParsedFunctionHelper::FinalizeCompilation(
          ++i) {
       thread()->cha()->leaf_classes()[i]->RegisterCHACode(code);
     }
-    for (intptr_t i = 0;
-         i < flow_graph->guarded_fields()->length();
-         i++) {
-      const Field* field = (*flow_graph->guarded_fields())[i];
+    const ZoneGrowableArray<const Field*>& guarded_fields =
+        *flow_graph->parsed_function().guarded_fields();
+    for (intptr_t i = 0; i < guarded_fields.length(); i++) {
+      const Field* field = guarded_fields[i];
       field->RegisterDependentCode(code);
     }
   } else {  // not optimized.