Fix the flag --reorder-basic-blocks so it works to disable reordering.

runtime/vm/flow_graph.cc

Index: runtime/vm/flow_graph.cc
diff --git a/runtime/vm/flow_graph.cc b/runtime/vm/flow_graph.cc
index 36c148dc226dee8bd86c6feb353a9122ac491d10..e7f4293078ec5ed00a4272833b117e1388e05329 100644
--- a/runtime/vm/flow_graph.cc
+++ b/runtime/vm/flow_graph.cc
@@ -12,6 +12,7 @@
 
 namespace dart {
 
+DECLARE_FLAG(bool, reorder_basic_blocks);
 DECLARE_FLAG(bool, trace_optimization);
 DECLARE_FLAG(bool, verify_compiler);
 DEFINE_FLAG(bool, optimize_try_catch, true, "Optimization of try-catch");
@@ -41,6 +42,14 @@ FlowGraph::FlowGraph(const FlowGraphBuilder& builder,
 }
 
 
+GrowableArray<BlockEntryInstr*>* FlowGraph::codegen_block_order(
+    bool is_optimized) {
+  return (is_optimized && FLAG_reorder_basic_blocks)
+      ? &optimized_block_order_
+      : &reverse_postorder_;
+}
+
+
 ConstantInstr* FlowGraph::GetConstant(const Object& object) {
   // Check if the constant is already in the pool.
   GrowableArray<Definition*>* pool = graph_entry_->initial_definitions();