Fix observe package to work with new barback logger.

pkg/observe/lib/transform.dart

 // Copyright (c) 2013, 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.
 
 /**
  * Code transform for @observable. The core transformation is relatively
  * straightforward, and essentially like an editor refactoring.
  */
 library observe.transform;
 
@@ skipping 50 matching lines @@
 }
 
 TextEditTransaction _transformCompilationUnit(
     String inputCode, SourceFile sourceFile, TransformLogger logger) {
   var unit = _parseCompilationUnit(inputCode);
   var code = new TextEditTransaction(inputCode, sourceFile);
   for (var directive in unit.directives) {
     if (directive is LibraryDirective && _hasObservable(directive)) {
       logger.warning('@observable on a library no longer has any effect. '
           'It should be placed on individual fields.',
-          _getSpan(sourceFile, directive));
+          span: _getSpan(sourceFile, directive));
       break;
     }
   }
 
   for (var declaration in unit.declarations) {
     if (declaration is ClassDeclaration) {
       _transformClass(declaration, code, sourceFile, logger);
     } else if (declaration is TopLevelVariableDeclaration) {
       if (_hasObservable(declaration)) {
         logger.warning('Top-level fields can no longer be observable. '
             'Observable fields should be put in an observable objects.',
-            _getSpan(sourceFile, declaration));
+            span: _getSpan(sourceFile, declaration));
       }
     }
   }
   return code;
 }
 
 /** Parse [code] using analyzer_experimental. */
 CompilationUnit _parseCompilationUnit(String code) {
   var errorListener = new _ErrorCollector();
   var scanner = new StringScanner(null, code, errorListener);
@@ skipping 23 matching lines @@
   return node.metadata.any((m) => m.name.name == name &&
       m.constructorName == null && m.arguments == null);
 }
 
 void _transformClass(ClassDeclaration cls, TextEditTransaction code,
     SourceFile file, TransformLogger logger) {
 
   if (_hasObservable(cls)) {
     logger.warning('@observable on a class no longer has any effect. '
         'It should be placed on individual fields.',
-        _getSpan(file, cls));
+        span: _getSpan(file, cls));
   }
 
   // We'd like to track whether observable was declared explicitly, otherwise
   // report a warning later below. Because we don't have type analysis (only
   // syntactic understanding of the code), we only report warnings that are
   // known to be true.
   var declaresObservable = false;
   if (cls.extendsClause != null) {
     var id = _getSimpleIdentifier(cls.extendsClause.superclass.name);
     if (id.name == 'ObservableBase') {
@@ skipping 37 matching lines @@
   var instanceFields = new Set<String>();
   var getters = new List<String>();
   var setters = new List<String>();
 
   for (var member in cls.members) {
     if (member is FieldDeclaration) {
       if (member.isStatic) {
         if (_hasObservable(member)){
           logger.warning('Static fields can no longer be observable. '
               'Observable fields should be put in an observable objects.',
-              _getSpan(file, member));
+              span: _getSpan(file, member));
         }
         continue;
       }
       if (_hasObservable(member)) {
         if (!declaresObservable) {
           logger.warning('Observable fields should be put in an observable '
               'objects. Please declare that this class extends from '
               'ObservableBase, includes ObservableMixin, or implements '
               'Observable.',
-              _getSpan(file, member));
+              span: _getSpan(file, member));
         }
         _transformFields(file, member, code, logger);
 
         var names = member.fields.variables.map((v) => v.name.name);
 
         getters.addAll(names);
         if (!_isReadOnly(member.fields)) {
           setters.addAll(names);
           instanceFields.addAll(names);
         }
@@ skipping 91 matching lines @@
     TextEditTransaction code, TransformLogger logger) {
 
   final fields = member.fields;
   if (_isReadOnly(fields)) return;
 
   // Private fields aren't supported:
   for (var field in fields.variables) {
     final name = field.name.name;
     if (Identifier.isPrivateName(name)) {
       logger.warning('Cannot make private field $name observable.',
-          _getSpan(file, field));
+          span: _getSpan(file, field));
       return;
     }
   }
 
   // Unfortunately "var" doesn't work in all positions where type annotations
   // are allowed, such as "var get name". So we use "dynamic" instead.
   var type = 'dynamic';
   if (fields.type != null) {
     type = _getOriginalCode(code, fields.type);
   } else if (_hasKeyword(fields.keyword, Keyword.VAR)) {
@@ skipping 54 matching lines @@
 
 Token _findFieldSeperator(Token token) {
   while (token != null) {
     if (token.type == TokenType.COMMA || token.type == TokenType.SEMICOLON) {
       break;
     }
     token = token.next;
   }
   return token;
 }