Re-apply "What if you closurize identical?" but this time don't be magic: it requires the compiler …

sdk/lib/_internal/compiler/implementation/lib/core_patch.dart

Index: sdk/lib/_internal/compiler/implementation/lib/core_patch.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/lib/core_patch.dart	(revision 16786)
+++ sdk/lib/_internal/compiler/implementation/lib/core_patch.dart	(working copy)
@@ -249,6 +249,4 @@
 }
 
 // Patch for 'identical' function.
-patch bool identical(Object a, Object b) {
-  throw new Error('Should not reach the body of identical');
-}
+patch bool identical(Object a, Object b) => Primitives.identical(a, b);