Fix an assertion about canonical types in the precompiler.

runtime/vm/precompiler.cc

Index: runtime/vm/precompiler.cc
diff --git a/runtime/vm/precompiler.cc b/runtime/vm/precompiler.cc
index 13c2b686ba2ada7d417bdada49ba38efb8234fbd..29b4d22b865935ce91868df2e9cda8dde497676d 100644
--- a/runtime/vm/precompiler.cc
+++ b/runtime/vm/precompiler.cc
@@ -2677,7 +2677,7 @@ void Precompiler::RehashTypes() {
   {
     CanonicalTypeSet types_table(Z, object_store->canonical_types());
     types_array = HashTables::ToArray(types_table, false);
-    for (intptr_t i = 0; i < (types_array.Length() - 1); i++) {
+    for (intptr_t i = 0; i < types_array.Length(); i++) {
       type ^= types_array.At(i);
       types.Add(type);
     }
@@ -2690,7 +2690,7 @@ void Precompiler::RehashTypes() {
   for (intptr_t i = 0; i < types.Length(); i++) {
     type ^= types.At(i);
     bool present = types_table.Insert(type);
-    ASSERT(!present);
+    ASSERT(!present || type.IsRecursive());
   }
   object_store->set_canonical_types(types_table.Release());
 
@@ -2703,7 +2703,7 @@ void Precompiler::RehashTypes() {
     CanonicalTypeArgumentsSet typeargs_table(
         Z, object_store->canonical_type_arguments());
     typeargs_array = HashTables::ToArray(typeargs_table, false);
-    for (intptr_t i = 0; i < (typeargs_array.Length() - 1); i++) {
+    for (intptr_t i = 0; i < typeargs_array.Length(); i++) {
       typearg ^= typeargs_array.At(i);
       typeargs.Add(typearg);
     }
@@ -2717,7 +2717,7 @@ void Precompiler::RehashTypes() {
   for (intptr_t i = 0; i < typeargs.Length(); i++) {
     typearg ^= typeargs.At(i);
     bool present = typeargs_table.Insert(typearg);
-    ASSERT(!present);
+    ASSERT(!present || typearg.IsRecursive());
   }
   object_store->set_canonical_type_arguments(typeargs_table.Release());
 }