- Ensure that the token stream from generated source matches the

runtime/lib/errors_patch.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.
 
 patch class Error {
   /* patch */ static String _objectToString(Object object) {
     return Object._toString(object);
   }
 
   /* patch */ StackTrace get stackTrace => _stackTrace;
 
   StackTrace _stackTrace;
 }
 
 patch class AssertionError extends Error {
   AssertionError._create(
       this._failedAssertion, this._url, this._line, this._column);
 
   static _throwNew(int assertionStart, int assertionEnd)
       native "AssertionError_throwNew";
 
   String toString() {
-    return "'$_url': Failed assertion: line $_line pos $_column: "
+    var columnInfo = "";
+    if (_column > 0) {
+      // Only add column information if it is valid.
+      columnInfo = " pos $_column";
+    }
+    return "'$_url': Failed assertion: line $_line$columnInfo: "
         "'$_failedAssertion' is not true.";
   }
   final String _failedAssertion;
   final String _url;
   final int _line;
   final int _column;
 }
 
 patch class TypeError extends AssertionError {
   TypeError._create(String url, int line, int column,
@@ skipping 270 matching lines @@
     return msg_buf.toString();
   }
 }
 
 class _JavascriptIntegerOverflowError extends Error {
   final Object _value;
 
   _JavascriptIntegerOverflowError(this._value);
   String toString() => "Javascript Integer Overflow: $_value";
 }