Rehash canonical constants table for each class that can be affected by the 'become' operation

runtime/vm/verifier.cc

Index: runtime/vm/verifier.cc
diff --git a/runtime/vm/verifier.cc b/runtime/vm/verifier.cc
index 5bc47657c107261cc2e1ae74b2218ed1d2de3b8c..fc1186764e5331819f20d61aa226e22b4575cdde 100644
--- a/runtime/vm/verifier.cc
+++ b/runtime/vm/verifier.cc
@@ -92,7 +92,12 @@ void VerifyCanonicalVisitor::VisitObject(RawObject* obj) {
   if (obj->GetClassId() >= kInstanceCid) {
     if (obj->IsCanonical()) {
       instanceHandle_ ^= obj;
-      ASSERT(instanceHandle_.CheckIsCanonical(thread_));
+      const bool is_canonical = instanceHandle_.CheckIsCanonical(thread_);
+      if (!is_canonical) {
+        OS::PrintErr("Instance `%s` is not canonical!\n",
+                     instanceHandle_.ToCString());
+      }
+      ASSERT(is_canonical);
     }
   }
 }