Fixup redefinitions before doing code motion

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 9c1c08e2b295640945be08162110a88adcfe37cc..9e20957a71315133fefa1a5c8c8a6d1bb97efeec 100644
--- a/runtime/vm/flow_graph.h
+++ b/runtime/vm/flow_graph.h
@@ -199,6 +199,7 @@ class FlowGraph : public ZoneAllocated {
 
   // Verification methods for debugging.
   bool VerifyUseLists();
+  bool VerifyRedefinitions();
 
   void DiscoverBlocks();
 
@@ -291,6 +292,10 @@ class FlowGraph : public ZoneAllocated {
                                   Instruction* dom,
                                   Definition* other);
 
+  // Renames uses of redefined values to make sure that uses of redefined
+  // values that are dominated by a redefinition are renamed.
+  void RenameUsesDominatedByRedefinitions();
+
  private:
   friend class IfConverter;
   friend class BranchSimplifier;