Run canonicalization again after constant propagation.

runtime/vm/compiler.cc

Index: runtime/vm/compiler.cc
diff --git a/runtime/vm/compiler.cc b/runtime/vm/compiler.cc
index d462881fee0e42a6bd6c5c80b6260677ed23481b..69e579e552e783a0a900e0285c1d792b14a5a549 100644
--- a/runtime/vm/compiler.cc
+++ b/runtime/vm/compiler.cc
@@ -209,6 +209,8 @@ static bool CompileParsedFunctionHelper(const ParsedFunction& parsed_function,
         }
         if (FLAG_constant_propagation) {
           ConstantPropagator::Optimize(flow_graph);
+          // A canonicalization pass to remove e.g. smi checks on smi constants.
+          optimizer.OptimizeComputations();
         }
         if (FLAG_common_subexpression_elimination) {
           DominatorBasedCSE::Optimize(flow_graph);