Update web/ samples to work with Flutter SDK (#134)

* add package:http dependency in dad_jokes

* add package:http dependency in filipino_cuisine

* don't build package:http demos until flutter/flutter#34858 is resolved

* update gallery

* update github_dataviz

* update particle_background

* don't build github_dataviz (uses package:http)

* update slide_puzzle

* update spinning_square

* update timeflow

* update vision_challenge

* update charts

* update dad_jokes

* update filipino cuisine

* ignore build output

* update timeflow and vision_challenge

* update slide_puzzle

* don't commit build/ directory

* move preview.png images to assets

* fix path url join

* update readme

* update web/readme.md

web/gallery/lib/demo/material/progress_indicator_demo.dart

@@ -1,8 +1,8 @@
-// Copyright 2018 The Chromium Authors. All rights reserved.
+// Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter_web/material.dart';
+import 'package:flutter/material.dart';
 
 import '../../gallery/demo.dart';
 
@@ -13,8 +13,7 @@ class ProgressIndicatorDemo extends StatefulWidget {
   _ProgressIndicatorDemoState createState() => _ProgressIndicatorDemoState();
 }
 
-class _ProgressIndicatorDemoState extends State<ProgressIndicatorDemo>
-    with SingleTickerProviderStateMixin {
+class _ProgressIndicatorDemoState extends State<ProgressIndicatorDemo> with SingleTickerProviderStateMixin {
   AnimationController _controller;
   Animation<double> _animation;
 
@@ -28,14 +27,15 @@ class _ProgressIndicatorDemoState extends State<ProgressIndicatorDemo>
     )..forward();
 
     _animation = CurvedAnimation(
-        parent: _controller,
-        curve: const Interval(0.0, 0.9, curve: Curves.fastOutSlowIn),
-        reverseCurve: Curves.fastOutSlowIn)
-      ..addStatusListener((AnimationStatus status) {
-        if (status == AnimationStatus.dismissed)
-          _controller.forward();
-        else if (status == AnimationStatus.completed) _controller.reverse();
-      });
+      parent: _controller,
+      curve: const Interval(0.0, 0.9, curve: Curves.fastOutSlowIn),
+      reverseCurve: Curves.fastOutSlowIn,
+    )..addStatusListener((AnimationStatus status) {
+      if (status == AnimationStatus.dismissed)
+        _controller.forward();
+      else if (status == AnimationStatus.completed)
+        _controller.reverse();
+    });
   }
 
   @override
@@ -66,7 +66,10 @@ class _ProgressIndicatorDemoState extends State<ProgressIndicatorDemo>
 
   Widget _buildIndicators(BuildContext context, Widget child) {
     final List<Widget> indicators = <Widget>[
-      const SizedBox(width: 200.0, child: LinearProgressIndicator()),
+      const SizedBox(
+        width: 200.0,
+        child: LinearProgressIndicator(),
+      ),
       const LinearProgressIndicator(),
       const LinearProgressIndicator(),
       LinearProgressIndicator(value: _animation.value),
@@ -77,23 +80,22 @@ class _ProgressIndicatorDemoState extends State<ProgressIndicatorDemo>
           SizedBox(
               width: 20.0,
               height: 20.0,
-              child: CircularProgressIndicator(value: _animation.value)),
+              child: CircularProgressIndicator(value: _animation.value),
+          ),
           SizedBox(
             width: 100.0,
             height: 20.0,
             child: Text('${(_animation.value * 100.0).toStringAsFixed(1)}%',
-                textAlign: TextAlign.right),
+              textAlign: TextAlign.right,
+            ),
           ),
         ],
       ),
     ];
     return Column(
       children: indicators
-          .map<Widget>((Widget c) => Container(
-              child: c,
-              margin:
-                  const EdgeInsets.symmetric(vertical: 15.0, horizontal: 20.0)))
-          .toList(),
+        .map<Widget>((Widget c) => Container(child: c, margin: const EdgeInsets.symmetric(vertical: 15.0, horizontal: 20.0)))
+        .toList(),
     );
   }
 
@@ -102,9 +104,7 @@ class _ProgressIndicatorDemoState extends State<ProgressIndicatorDemo>
     return Scaffold(
       appBar: AppBar(
         title: const Text('Progress indicators'),
-        actions: <Widget>[
-          MaterialDemoDocumentationButton(ProgressIndicatorDemo.routeName)
-        ],
+        actions: <Widget>[MaterialDemoDocumentationButton(ProgressIndicatorDemo.routeName)],
       ),
       body: Center(
         child: SingleChildScrollView(
@@ -117,10 +117,11 @@ class _ProgressIndicatorDemoState extends State<ProgressIndicatorDemo>
                 top: false,
                 bottom: false,
                 child: Container(
-                  padding: const EdgeInsets.symmetric(
-                      vertical: 12.0, horizontal: 8.0),
+                  padding: const EdgeInsets.symmetric(vertical: 12.0, horizontal: 8.0),
                   child: AnimatedBuilder(
-                      animation: _animation, builder: _buildIndicators),
+                    animation: _animation,
+                    builder: _buildIndicators,
+                  ),
                 ),
               ),
             ),