Types with identical object identities are always related

Author: ahejlsberg

src/compiler/checker.ts

@@ -20609,6 +20609,8 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
          * * Ternary.False if they are not related.
          */
         function isRelatedTo(originalSource: Type, originalTarget: Type, recursionFlags: RecursionFlags = RecursionFlags.Both, reportErrors = false, headMessage?: DiagnosticMessage, intersectionState = IntersectionState.None): Ternary {
+            if (originalSource === originalTarget) return Ternary.True;
+
             // Before normalization: if `source` is type an object type, and `target` is primitive,
             // skip all the checks we don't need and just return `isSimpleTypeRelatedTo` result
             if (originalSource.flags & TypeFlags.Object && originalTarget.flags & TypeFlags.Primitive) {