Consider 'object' a valid base type + apparent type of 'object' is {}

Author: ahejlsberg

src/compiler/checker.ts

@@ -3991,7 +3991,7 @@ namespace ts {
         // A valid base type is any non-generic object type or intersection of non-generic
         // object types.
         function isValidBaseType(type: Type): boolean {
-            return type.flags & TypeFlags.Object && !isGenericMappedType(type) ||
+            return type.flags & (TypeFlags.Object | TypeFlags.NonPrimitive) && !isGenericMappedType(type) ||
                 type.flags & TypeFlags.Intersection && !forEach((<IntersectionType>type).types, t => !isValidBaseType(t));
         }
 
@@ -4944,7 +4944,7 @@ namespace ts {
                 t.flags & TypeFlags.NumberLike ? globalNumberType :
                 t.flags & TypeFlags.BooleanLike ? globalBooleanType :
                 t.flags & TypeFlags.ESSymbol ? getGlobalESSymbolType() :
-                t.flags & TypeFlags.NonPrimitive ? globalObjectType :
+                t.flags & TypeFlags.NonPrimitive ? emptyObjectType :
                 t;
         }