Move NullError into interceptors

pkg/dev_compiler/tool/input_sdk/private/interceptors.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart._interceptors;
 
 import 'dart:collection';
 import 'dart:_internal' hide Symbol;
 import 'dart:_js_helper';
 import 'dart:_foreign_helper' show JS;
@@ skipping 76 matching lines @@
  * non-trivial prototype chain.
  *
  * This class also serves as a fallback for unknown JavaScript exceptions.
  */
 class UnknownJavaScriptObject extends JavaScriptObject {
   const UnknownJavaScriptObject();
 
   String toString() => JS('String', 'String(#)', this);
 }
 
+// Note that this needs to be in interceptors.dart in order for
+// it to be picked up as an extension type.
+@JsPeerInterface(name: 'TypeError')
+class NullError extends Interceptor implements NoSuchMethodError {
+  StackTrace get stackTrace => Primitives.extractStackTrace(this);
+
+  String toString() {
+    // TODO(vsm): Distinguish between null reference errors and other
+    // TypeErrors.  We should not get non-null TypeErrors from DDC code,
+    // but we may from native JavaScript.
+    var message = JS('String', '#.message', this);
+    return "NullError: $message";
+  }
+}
+
 // Obsolete in dart dev compiler. Added only so that the same version of
 // dart:html can be used in dart2js an dev compiler.
 // Warning: calls to these methods need to be removed before custom elements
 // and cross-frame dom objects behave correctly in ddc.
 // See https://github.com/dart-lang/sdk/issues/28326
 findInterceptorConstructorForType(Type type) {}
 findConstructorForNativeSubclassType(Type type, String name) {}
 getNativeInterceptor(object) {}
 setDispatchProperty(object, value) {}