Make default_parameter_values a ZoneGrowableArray instead of an array in new space

runtime/vm/flow_graph_compiler_ia32.cc

Index: runtime/vm/flow_graph_compiler_ia32.cc
diff --git a/runtime/vm/flow_graph_compiler_ia32.cc b/runtime/vm/flow_graph_compiler_ia32.cc
index 2902aba11eb2c6512579fd2ec56c65971123e4a9..c11c45ee38541466c2d9a17be7772285322bfc55 100644
--- a/runtime/vm/flow_graph_compiler_ia32.cc
+++ b/runtime/vm/flow_graph_compiler_ia32.cc
@@ -884,9 +884,8 @@ void FlowGraphCompiler::CopyParameters() {
       __ jmp(&assign_optional_parameter, Assembler::kNearJump);
       __ Bind(&load_default_value);
       // Load EAX with default argument.
-      const Object& value = Object::ZoneHandle(zone(),
-          parsed_function().default_parameter_values().At(
-              param_pos - num_fixed_params));
+      const Instance& value =
+          parsed_function().DefaultParameterAt(param_pos - num_fixed_params);
       __ LoadObject(EAX, value);
       __ Bind(&assign_optional_parameter);
       // Assign EAX to fp[kFirstLocalSlotFromFp - param_pos].
@@ -919,8 +918,7 @@ void FlowGraphCompiler::CopyParameters() {
       __ cmpl(ECX, Immediate(param_pos));
       __ j(GREATER, &next_parameter, Assembler::kNearJump);
       // Load EAX with default argument.
-      const Object& value = Object::ZoneHandle(zone(),
-          parsed_function().default_parameter_values().At(i));
+      const Object& value = parsed_function().DefaultParameterAt(i);
       __ LoadObject(EAX, value);
       // Assign EAX to fp[kFirstLocalSlotFromFp - param_pos].
       // We do not use the final allocation index of the variable here, i.e.