Collect edge count profiling data and reorder basic blocks.

runtime/vm/flow_graph.h

Index: runtime/vm/flow_graph.h
diff --git a/runtime/vm/flow_graph.h b/runtime/vm/flow_graph.h
index 57fe60fca4c63c827c48ffad93746dbd44aca1ed..4a841968554bc0ebcdb4624083d58e863f7e19e5 100644
--- a/runtime/vm/flow_graph.h
+++ b/runtime/vm/flow_graph.h
@@ -78,6 +78,9 @@ class FlowGraph : public ZoneAllocated {
   const GrowableArray<BlockEntryInstr*>& reverse_postorder() const {
     return reverse_postorder_;
   }
+  GrowableArray<BlockEntryInstr*>* codegen_block_order(bool is_optimized) {
+    return is_optimized ? &optimized_block_order_ : &reverse_postorder_;
+  }
 
   // Iterators.
   BlockIterator reverse_postorder_iterator() const {
@@ -249,6 +252,7 @@ class FlowGraph : public ZoneAllocated {
   GrowableArray<BlockEntryInstr*> preorder_;
   GrowableArray<BlockEntryInstr*> postorder_;
   GrowableArray<BlockEntryInstr*> reverse_postorder_;
+  GrowableArray<BlockEntryInstr*> optimized_block_order_;
   ConstantInstr* constant_null_;
 
   BlockEffects* block_effects_;