Correct report unchanged formatting when reading from stdin. (#604)

* Correct report unchanged formatting when reading from stdin.

* Typo.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 27a1069..9638bed 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@
 * Don't split after `<` when a collection is in statement position (#589).
 * Force a split if the cascade target has non-obvious precedence (#590).
 * Split more often if a cascade target contains a split (#591).
+* Correctly report unchanged formatting when reading from stdin.
 
 # 0.2.16
 
diff --git a/bin/format.dart b/bin/format.dart
index e1eabbc..512928b 100644
--- a/bin/format.dart
+++ b/bin/format.dart
@@ -197,8 +197,8 @@
           selectionStart: selectionStart,
           selectionLength: selectionLength);
       var output = formatter.formatSource(source);
-      options.reporter
-          .afterFile(null, "<stdin>", output, changed: source != output);
+      options.reporter.afterFile(null, "<stdin>", output,
+          changed: source.text != output.text);
       return;
     } on FormatterException catch (err) {
       stderr.writeln(err.message());