Factor out code that looks up a canonical type and adds it to the canonical_types_ array if necessa…

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index aefc98b50a51e8b256f8a193814e0172c134bef9..7c20cae3d325d3e57d4bb0243fcd842d0a51f9ab 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -1488,6 +1488,9 @@ class Class : public Object {
       TrailPtr bound_trail,
       Heap::Space space);
 
+  RawAbstractType* LookupOrAddCanonicalType(const AbstractType& type,
+                                            intptr_t start_index) const;
+
   FINAL_HEAP_OBJECT_IMPLEMENTATION(Class, Object);
   friend class AbstractType;
   friend class Instance;