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/slide_puzzle/lib/src/core/body.dart

@@ -1,7 +1,3 @@
-// Copyright 2019 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 'dart:math' show Point;
 
 const zeroPoint = Point<double>(0, 0);

web/slide_puzzle/lib/src/core/point_int.dart

@@ -1,7 +1,3 @@
-// Copyright 2019 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 'dart:math' as math;
 
 class Point extends math.Point<int> {

web/slide_puzzle/lib/src/core/puzzle.dart

@@ -1,7 +1,3 @@
-// Copyright 2019 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 'dart:collection';
 import 'dart:convert';
 import 'dart:math' show Random, max;
@@ -127,7 +123,8 @@ abstract class Puzzle {
         value += delta * delta;
       }
     }
-    return value * incorrectTiles;
+    value *= incorrectTiles;
+    return value;
   }
 
   Puzzle clickRandom({bool vertical}) {
@@ -140,8 +137,8 @@ abstract class Puzzle {
 
   List<int> clickableValues({bool vertical}) {
     final open = openPosition();
-    final doRow = vertical == null || vertical == false;
-    final doColumn = vertical == null || vertical;
+    final doRow = (vertical == null || vertical == false);
+    final doColumn = (vertical == null || vertical);
 
     final values =
         Uint8List((doRow ? (width - 1) : 0) + (doColumn ? (height - 1) : 0));

web/slide_puzzle/lib/src/core/puzzle_animator.dart

@@ -1,13 +1,34 @@
-// Copyright 2019 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 'dart:async';
 import 'dart:math' show Point, Random;
 
 import 'body.dart';
 import 'puzzle.dart';
-import 'puzzle_proxy.dart';
+
+enum PuzzleEvent { click, reset, noop }
+
+abstract class PuzzleProxy {
+  int get width;
+
+  int get height;
+
+  int get length;
+
+  bool get solved;
+
+  void reset();
+
+  void clickOrShake(int tileValue);
+
+  int get tileCount;
+
+  int get clickCount;
+
+  int get incorrectTiles;
+
+  Point<double> location(int index);
+
+  bool isCorrectPosition(int value);
+}
 
 class PuzzleAnimator implements PuzzleProxy {
   final _rnd = Random();
@@ -36,10 +57,13 @@ class PuzzleAnimator implements PuzzleProxy {
   @override
   int get tileCount => _puzzle.tileCount;
 
+  @override
   int get incorrectTiles => _puzzle.incorrectTiles;
 
+  @override
   int get clickCount => _clickCount;
 
+  @override
   void reset() => _resetCore();
 
   Stream<PuzzleEvent> get onEvent => _controller.stream;
@@ -69,7 +93,7 @@ class PuzzleAnimator implements PuzzleProxy {
     _puzzle = _puzzle.clickRandom(vertical: _nextRandomVertical);
     _nextRandomVertical = !_nextRandomVertical;
     _clickCount++;
-    _controller.add(PuzzleEvent.random);
+    _controller.add(PuzzleEvent.click);
   }
 
   @override
@@ -141,7 +165,7 @@ class PuzzleAnimator implements PuzzleProxy {
       final delta = _puzzle.openPosition() - _puzzle.coordinatesOf(tileValue);
       deltaDouble = Point(delta.x.toDouble(), delta.y.toDouble());
     }
-    deltaDouble *= 0.5 / deltaDouble.magnitude;
+    deltaDouble *= (0.5 / deltaDouble.magnitude);
 
     _locations[tileValue].kick(deltaDouble);
   }

web/slide_puzzle/lib/src/core/puzzle_proxy.dart

@@ -1,25 +0,0 @@
-// Copyright 2019 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 'dart:math' show Point;
-
-enum PuzzleEvent { click, random, reset, noop }
-
-abstract class PuzzleProxy {
-  int get width;
-
-  int get height;
-
-  int get length;
-
-  bool get solved;
-
-  void clickOrShake(int tileValue);
-
-  int get tileCount;
-
-  Point<double> location(int index);
-
-  bool isCorrectPosition(int value);
-}

web/slide_puzzle/lib/src/core/puzzle_simple.dart

@@ -1,7 +1,3 @@
-// Copyright 2019 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.
-
 part of 'puzzle.dart';
 
 class _PuzzleSimple extends Puzzle {

web/slide_puzzle/lib/src/core/puzzle_smart.dart

@@ -1,7 +1,3 @@
-// Copyright 2019 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.
-
 part of 'puzzle.dart';
 
 mixin _SliceListMixin on ListMixin<int> {

web/slide_puzzle/lib/src/core/util.dart

@@ -1,7 +1,3 @@
-// Copyright 2019 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.
-
 void requireArgument(bool truth, String argName, [String message]) {
   if (!truth) {
     if (message == null || message.isEmpty) {