dart2js: Inline Primitives.identicalImplementation into identical patch.

sdk/lib/_internal/js_runtime/lib/core_patch.dart

Index: sdk/lib/_internal/js_runtime/lib/core_patch.dart
diff --git a/sdk/lib/_internal/js_runtime/lib/core_patch.dart b/sdk/lib/_internal/js_runtime/lib/core_patch.dart
index 971b37f96e36270c2b6726a7f0ba5f2b83033563..6db46cad476764515da19610049d188077021343 100644
--- a/sdk/lib/_internal/js_runtime/lib/core_patch.dart
+++ b/sdk/lib/_internal/js_runtime/lib/core_patch.dart
@@ -19,6 +19,8 @@ import 'dart:_js_helper' show patch,
                               objectHashCode,
                               Closure;
 
+import 'dart:_foreign_helper' show JS;
+
 import 'dart:_native_typed_data' show NativeUint8List;
 
 String _symbolToString(Symbol symbol) => _symbol_dev.Symbol.getName(symbol);
@@ -400,7 +402,7 @@ class RegExp {
 // Patch for 'identical' function.
 @patch
 bool identical(Object a, Object b) {
-  return Primitives.identicalImplementation(a, b);
+  return JS('bool', '(# == null ? # == null : # === #)', a, b, a, b);
 }
 
 @patch