Minor fixes in comments and style.

packages/flutter/lib/src/http/http.dart

@@ -4,7 +4,7 @@
 
 /// A [Future]-based library for making HTTP requests.
 ///
-/// Let library is based on Dart's `http` package, but we have removed the
+/// This library is based on Dart's `http` package, but we have removed the
 /// dependency on mirrors and added a `mojo`-based HTTP client.
 library http;
 

packages/flutter/lib/src/painting/box_painter.dart

@@ -644,7 +644,8 @@ class BackgroundImage {
 
   final List<VoidCallback> _listeners = <VoidCallback>[];
 
-  /// Adds a listener for background-image changes (e.g., arrives from the network).
+  /// Adds a listener for background-image changes (e.g., for when it arrives
+  /// from the network).
   void _addChangeListener(VoidCallback listener) {
     // We add the listener to the _imageResource first so that the first change
     // listener doesn't get callback synchronously if the image resource is

packages/flutter/lib/src/rendering/auto_layout.dart

@@ -12,8 +12,14 @@ import 'object.dart';
 /// variables. Used as a mixin by layout containers and parent data instances
 /// of render boxes taking part in auto layout.
 abstract class _AutoLayoutParamMixin {
-  // Ideally, the edges would all be final, but then they would have to be
-  // initialized before the constructor. Not sure how to do that using a Mixin.
+
+  void _setupLayoutParameters(dynamic context) {
+    _leftEdge = new al.Param.withContext(context);
+    _rightEdge = new al.Param.withContext(context);
+    _topEdge = new al.Param.withContext(context);
+    _bottomEdge = new al.Param.withContext(context);
+  }
+
   al.Param _leftEdge;
   al.Param _rightEdge;
   al.Param _topEdge;
@@ -32,13 +38,6 @@ abstract class _AutoLayoutParamMixin {
   al.Expression get horizontalCenter => (_leftEdge + _rightEdge) / al.cm(2.0);
   al.Expression get verticalCenter => (_topEdge + _bottomEdge) / al.cm(2.0);
 
-  void _setupLayoutParameters(dynamic context) {
-    _leftEdge = new al.Param.withContext(context);
-    _rightEdge = new al.Param.withContext(context);
-    _topEdge = new al.Param.withContext(context);
-    _bottomEdge = new al.Param.withContext(context);
-  }
-
   void _setupEditVariablesInSolver(al.Solver solver, double priority) {
     solver.addEditVariables(<al.Variable>[
         _leftEdge.variable,