Improve error reporting: use colors and associate the appropiate file with

pkg/compiler/lib/src/source_file_provider.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.
 
 library source_file_provider;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 import 'dart:math' as math;
@@ skipping 371 matching lines @@
 class BazelInputProvider extends SourceFileProvider {
   final List<Uri> dirs;
 
   BazelInputProvider(List<String> searchPaths)
     : dirs = searchPaths.map(_resolve).toList();
 
   static _resolve(String path) => currentDirectory.resolve(path);
 
   @override
   Future readFromUri(Uri uri) async {
+    var resolvedUri = uri;
     var path = uri.path;
     if (path.startsWith('/bazel-root')) {
       path = path.substring('/bazel-root/'.length);
       for (var dir in dirs) {
         var file = dir.resolve(path);
         if (await new File.fromUri(file).exists()) {
-          uri = file;
+          resolvedUri = file;
           break;
         }
       }
     }
-    return readUtf8BytesFromUri(uri);
+    var result = await readUtf8BytesFromUri(resolvedUri);
+    sourceFiles[uri] = sourceFiles[resolvedUri];
+    return result;
   }
 }