Fix various bugs in the type systems, and improve test coverage.

src/types.h

Index: src/types.h
diff --git a/src/types.h b/src/types.h
index 0161582e2023854f45076f9ebb1e817d3e8a4f74..16d80b8f8d44a314da3cae77d276b3f6545b38dc 100644
--- a/src/types.h
+++ b/src/types.h
@@ -154,7 +154,7 @@ namespace internal {
   V(Receiver,            kObject | kProxy)                              \
   V(NonNumber,           kBoolean | kName | kNull | kReceiver |         \
                          kUndefined | kInternal)                        \
-  V(Any,                 kNumber | kNonNumber)
+  V(Any,                 -1)
 
 #define BITSET_TYPE_LIST(V) \
   MASK_BITSET_TYPE_LIST(V) \
@@ -220,6 +220,10 @@ class TypeImpl : public Config::Base {
     return Of(*value, region);
   }
 
+  bool IsInhabited() {
+    return !this->IsBitset() || IsInhabited(this->AsBitset());
+  }
+
   bool Is(TypeImpl* that) { return this == that || this->SlowIs(that); }
   template<class TypeHandle>
   bool Is(TypeHandle that) { return this->Is(*that); }