Introduce span with line context

test/file_test.dart

Index: test/file_test.dart
diff --git a/test/file_test.dart b/test/file_test.dart
index 114a17e44ba116d3895cffd270f0665c88d2f894..0ec05349ec912a1ed66a4b21a33c73cce4af5147 100644
--- a/test/file_test.dart
+++ b/test/file_test.dart
@@ -87,7 +87,7 @@ zip zap zop""", url: "foo.dart");
       test("column may not be outside the file", () {
         expect(() => file.getOffset(2, 100), throwsRangeError);
       });
- 
+
       test("column may not be outside the line", () {
         expect(() => file.getOffset(1, 20), throwsRangeError);
       });
@@ -109,8 +109,8 @@ zip zap zop""", url: "foo.dart");
 
     group("for span().union()", () {
       test("source URLs must match", () {
-        var other = new SourceSpan(
-            new SourceLocation(10), new SourceLocation(11), "_");
+        var other =
+            new SourceSpan(new SourceLocation(10), new SourceLocation(11), "_");
 
         expect(() => file.span(9, 10).union(other), throwsArgumentError);
       });
@@ -306,10 +306,8 @@ zip zap zop""", url: "bar.dart").span(10, 11);
       });
 
       test("returns a base SourceSpan for a SourceSpan input", () {
-        var other = new SourceSpan(
-            new SourceLocation(0, sourceUrl: "foo.dart"),
-            new SourceLocation(5, sourceUrl: "foo.dart"),
-            "hey, ");
+        var other = new SourceSpan(new SourceLocation(0, sourceUrl: "foo.dart"),
+            new SourceLocation(5, sourceUrl: "foo.dart"), "hey, ");
         var result = span.union(other);
         expect(result, isNot(new isInstanceOf<FileSpan>()));
         expect(result.start, equals(other.start));
@@ -367,4 +365,4 @@ zip zap zop""", url: "bar.dart").span(10, 11);
       });
     });
   });
-}
+}