Throw an exception when invalid source file location is encountered.

lib/compiler/implementation/warnings.dart

 // Copyright (c) 2011, 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.
 
 class MessageKind {
   final String template;
   const MessageKind(this.template);
 
   static const GENERIC = const MessageKind('#{1}');
 
@@ skipping 237 matching lines @@
 
   static const CANNOT_RESOLVE_SETTER = const MessageKind(
       'cannot resolve setter.');
 
   static const VOID_NOT_ALLOWED = const MessageKind(
       'type void is only allowed in a return type.');
 
   static const COMPILER_CRASHED = const MessageKind(
       "Error: The compiler crashed when compiling this element.");
 
+  static const INVALID_SOURCE_FILE_LOCATION = const MessageKind('''

[ahe, 2012/09/24 08:54:18]

Please add this above COMPILER_CRASHED.

[podivilov, 2012/09/24 09:44:01]

Done.

+Invalid offset (#{1}) in source map.
+File: #{2}
+Length: #{3}''');
+
   static const PLEASE_REPORT_THE_CRASH = const MessageKind('''
 The compiler is broken.
 
 When compiling the above element, the compiler crashed. It is not
 possible to tell if this is caused by a problem in your program or
 not. Regardless, the compiler should not crash.
 
 The Dart team would greatly appreciate if you would take a moment to
 report this problem at http://dartbug.com/new.
 
@@ skipping 74 matching lines @@
 
 class CompileTimeConstantError extends Diagnostic {
   CompileTimeConstantError(MessageKind kind, List arguments)
     : super(kind, arguments);
 }
 
 class CompilationError extends Diagnostic {
   CompilationError(MessageKind kind, List arguments)
     : super(kind, arguments);
 }