Unbox phis that were proven to be of type Double.

runtime/vm/flow_graph_optimizer.h

Index: runtime/vm/flow_graph_optimizer.h
diff --git a/runtime/vm/flow_graph_optimizer.h b/runtime/vm/flow_graph_optimizer.h
index 09a0d95b0ff15f0dc8ebe79a1bd442770e48ade2..ef14418ca9dfafdd4f436dd97f3b3797cda9e6f3 100644
--- a/runtime/vm/flow_graph_optimizer.h
+++ b/runtime/vm/flow_graph_optimizer.h
@@ -24,6 +24,10 @@ class FlowGraphOptimizer : public FlowGraphVisitor {
 
   void OptimizeComputations();
 
+  void EliminateDeadPhis();
+
+  void SelectRepresentations();
+
   virtual void VisitStaticCall(StaticCallComp* comp, BindInstr* instr);
   virtual void VisitInstanceCall(InstanceCallComp* comp, BindInstr* instr);
   virtual void VisitRelationalOp(RelationalOpComp* comp, BindInstr* instr);
@@ -61,6 +65,8 @@ class FlowGraphOptimizer : public FlowGraphVisitor {
                          Environment* env,
                          BindInstr::UseKind use_kind);
 
+  void InsertConversionsFor(Definition* def);
+
   FlowGraph* flow_graph_;
 
   DISALLOW_COPY_AND_ASSIGN(FlowGraphOptimizer);