Ensure that MaterializeObject has relaxed RequiredInputRepresentation.

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
diff --git a/runtime/vm/intermediate_language.h b/runtime/vm/intermediate_language.h
index 33320f3451dd78a8379087ac98c4ce1d3ef24514..b3bbd0b9fd26dad70466ee2b4c2d75e74e60c04e 100644
--- a/runtime/vm/intermediate_language.h
+++ b/runtime/vm/intermediate_language.h
@@ -4026,6 +4026,16 @@ class MaterializeObjectInstr : public Definition {
     return (*values_)[i];
   }
 
+  // SelectRepresentations pass is run once more while MaterializeObject
+  // instructions are still in the graph. To avoid any redundant boxing
+  // operations inserted by that pass we should indicate that this
+  // instruction can cope with any representation as it is essentially
+  // an environment use.
+  virtual Representation RequiredInputRepresentation(intptr_t idx) const {
+    ASSERT(0 <= idx && idx < InputCount());
+    return kNoRepresentation;
+  }
+
   virtual bool CanDeoptimize() const { return false; }
   virtual EffectSet Effects() const { return EffectSet::None(); }