Provide Type::Contains methods.

src/types.h

Index: src/types.h
diff --git a/src/types.h b/src/types.h
index 4569d131b157eb9bc7dce1ee8a01278d51c54e91..bfa9e67983b102eb81eb3bd289e3d49fc9c8a837 100644
--- a/src/types.h
+++ b/src/types.h
@@ -246,16 +246,23 @@ class TypeImpl : public Config::Base {
   bool Is(TypeImpl* that) { return this == that || this->SlowIs(that); }
   template<class TypeHandle>
   bool Is(TypeHandle that) { return this->Is(*that); }
+
   bool Maybe(TypeImpl* that);
   template<class TypeHandle>
   bool Maybe(TypeHandle that) { return this->Maybe(*that); }
 
+  // Equivalent to Constant(value)->Is(this), but avoiding allocation.
+  bool Contains(i::Object* val);
+  bool Contains(i::Handle<i::Object> val) { return this->Contains(*val); }
+
   // State-dependent versions of Of and Is that consider subtyping between
   // a constant and its map class.
-  static TypeHandle OfCurrently(i::Handle<i::Object> value, Region* region);
-  bool IsCurrently(TypeImpl* that);
+  static TypeHandle NowOf(i::Handle<i::Object> value, Region* region);
+  bool NowIs(TypeImpl* that);
   template<class TypeHandle>
-  bool IsCurrently(TypeHandle that)  { return this->IsCurrently(*that); }
+  bool NowIs(TypeHandle that)  { return this->NowIs(*that); }
+  bool NowContains(i::Object* val);
+  bool NowContains(i::Handle<i::Object> val) { return this->NowContains(*val); }
 
   bool IsClass() { return Config::is_class(this); }
   bool IsConstant() { return Config::is_constant(this); }