Introduce span with line context

test/location_test.dart

Index: test/location_test.dart
diff --git a/test/location_test.dart b/test/location_test.dart
index 1eedec43a14e3d74412ff23e7163925c0144ebda..8a5b67331073a49735bf2e8e0e8f90992d6ad0eb 100644
--- a/test/location_test.dart
+++ b/test/location_test.dart
@@ -8,8 +8,8 @@ import 'package:source_span/source_span.dart';
 main() {
   var location;
   setUp(() {
-    location = new SourceLocation(15,
-        line: 2, column: 6, sourceUrl: "foo.dart");
+    location =
+        new SourceLocation(15, line: 2, column: 6, sourceUrl: "foo.dart");
   });
 
   group('errors', () {
@@ -28,13 +28,13 @@ main() {
     });
 
     test('for distance() source URLs must match', () {
-      expect(() => location.distance(new SourceLocation(0)),
-          throwsArgumentError);
+      expect(
+          () => location.distance(new SourceLocation(0)), throwsArgumentError);
     });
 
     test('for compareTo() source URLs must match', () {
-      expect(() => location.compareTo(new SourceLocation(0)),
-          throwsArgumentError);
+      expect(
+          () => location.compareTo(new SourceLocation(0)), throwsArgumentError);
     });
   });
 
@@ -81,7 +81,6 @@ main() {
     });
   });
 
-
   group("equality", () {
     test("two locations with the same offset and source are equal", () {
       var other = new SourceLocation(15, sourceUrl: "foo.dart");