Update doc comments to follow style guide.

sdk/lib/_internal/pub/lib/src/progress.dart

Index: sdk/lib/_internal/pub/lib/src/progress.dart
diff --git a/sdk/lib/_internal/pub/lib/src/progress.dart b/sdk/lib/_internal/pub/lib/src/progress.dart
index d01e95278880552a710f9a6eb680e1b51b224e55..ad1ceb2582e54647ace864deca5fef59f5c76e93 100644
--- a/sdk/lib/_internal/pub/lib/src/progress.dart
+++ b/sdk/lib/_internal/pub/lib/src/progress.dart
@@ -18,8 +18,9 @@ class Progress {
   /// The [Stopwatch] used to track how long a progress log has been running.
   final _stopwatch = new Stopwatch();
 
-  /// The progress message as it's being incrementally appended. When the
-  /// progress is done, a single entry will be added to the log for it.
+  /// The progress message as it's being incrementally appended.
+  ///
+  /// When the progress is done, a single entry will be added to the log for it.
   final String _message;
 
   /// Gets the current progress time as a parenthesized, formatted string.