Move a number of packages and some of pub over to using source_span.

sdk/lib/_internal/pub/lib/src/barback/transformer_id.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 pub.barback.transformer_id;
 
 import 'dart:async';
 
 import 'package:barback/barback.dart';
 import 'package:path/path.dart' as p;
-import 'package:source_maps/source_maps.dart';
+import 'package:source_span/source_span.dart';
 
 import '../io.dart';
 import '../utils.dart';
 
 /// A list of the names of all built-in transformers that pub exposes.
 const _BUILT_IN_TRANSFORMERS = const ['\$dart2js'];
 
 /// An identifier that indicates the library that contains a transformer.
 ///
 /// It's possible that the library identified by [this] defines multiple
 /// transformers. If so, they're all always loaded in the same phase.
 class TransformerId {
   /// The package containing the library where the transformer is defined.
   final String package;
 
   /// The `/`-separated path to the library that contains this transformer.
   ///
   /// This is relative to the `lib/` directory in [package], and doesn't end in
   /// `.dart`.
   ///
   /// This can be null; if so, it indicates that the transformer(s) should be
   /// loaded from `lib/transformer.dart` if that exists, and `lib/$package.dart`
   /// otherwise.
   final String path;
 
   /// The source span from which this id was parsed.
-  final Span span;
+  final SourceSpan span;
 
   /// Whether this ID points to a built-in transformer exposed by pub.
   bool get isBuiltInTransformer => package.startsWith('\$');
 
   /// Parses a transformer identifier.
   ///
   /// A transformer identifier is a string of the form "package_name" or
   /// "package_name/path/to/library". It does not have a trailing extension. If
   /// it just has a package name, it expands to lib/transformer.dart if that
   /// exists, or lib/${package}.dart otherwise. Otherwise, it expands to
   /// lib/${path}.dart. In either case it's located in the given package.
-  factory TransformerId.parse(String identifier, Span span) {
+  factory TransformerId.parse(String identifier, SourceSpan span) {
     if (identifier.isEmpty) {
       throw new FormatException('Invalid library identifier: "".');
     }
 
     var parts = split1(identifier, "/");
     if (parts.length == 1) {
       return new TransformerId(parts.single, null, span);
     }
 
     return new TransformerId(parts.first, parts.last, span);
   }
 
   TransformerId(this.package, this.path, this.span) {
     if (!package.startsWith('\$')) return;
     if (_BUILT_IN_TRANSFORMERS.contains(package)) return;
-    throw new SpanFormatException('Unsupported built-in transformer $package.',
-        span);
+    throw new SourceSpanFormatException(
+        'Unsupported built-in transformer $package.', span);
   }
 
   bool operator==(other) =>
       other is TransformerId && other.package == package && other.path == path;
 
   int get hashCode => package.hashCode ^ path.hashCode;
 
   String toString() => path == null ? package : '$package/$path';
 
   /// Returns the asset id for the library identified by this transformer id.
@@ skipping 18 matching lines @@
   ///
   /// If `path` is null, this will determine which library to load.
   String getFullPath(String packageDir) {
     if (path != null) return p.join(packageDir, 'lib', p.fromUri('$path.dart'));
 
     var transformerPath = p.join(packageDir, 'lib', 'transformer.dart');
     if (fileExists(transformerPath)) return transformerPath;
     return p.join(packageDir, 'lib', '$package.dart');
   }
 }