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

pkg/compiler/lib/src/source_file_provider.dart

Index: pkg/compiler/lib/src/source_file_provider.dart
diff --git a/pkg/compiler/lib/src/source_file_provider.dart b/pkg/compiler/lib/src/source_file_provider.dart
index 95a45bf1db3d02395f25c49bb33a1b6b209886ec..588c970afbc921fe8fd16de0c4667bc3cccef438 100644
--- a/pkg/compiler/lib/src/source_file_provider.dart
+++ b/pkg/compiler/lib/src/source_file_provider.dart
@@ -389,17 +389,20 @@ class BazelInputProvider extends SourceFileProvider {
 
   @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;
   }
 }