Add constants for material colors and shadows

This CL removes the hard-coded colors and shadows from the fn widgets and
replaces them with compile-time constants. The color values are from the
material spec:

http://www.google.com/design/spec/style/color.html#color-color-palette

R=eseidel@chromium.org

Review URL: https://codereview.chromium.org/983733003

examples/fn/widgets/drawer.dart

@@ -103,7 +103,7 @@ class Drawer extends Component {
     left: 0;
     bottom: 0;
     right: 0;
-    box-shadow: 0 10px 20px rgba(0,0,0,0.19), 0 6px 6px rgba(0,0,0,0.23);'''
+    box-shadpw: ${Shadow[3]};'''
   );
 
   static Style _maskStyle = new Style('''
@@ -117,7 +117,7 @@ class Drawer extends Component {
   );
 
   static Style _contentStyle = new Style('''
-    background-color: #FAFAFA;
+    background-color: ${Grey[50]};
     will-change: transform;
     position: absolute;
     z-index: 3;

examples/fn/widgets/drawerheader.dart

@@ -7,7 +7,7 @@ class DrawerHeader extends Component {
     flex-direction: column;
     height: 140px;
     -webkit-user-select: none;
-    background-color: #E3ECF5;
+    background-color: ${BlueGrey[50]};
     border-bottom: 1px solid #D1D9E1;
     padding-bottom: 7px;
     margin-bottom: 8px;'''

examples/fn/widgets/floating_action_button.dart

@@ -12,7 +12,7 @@ class FloatingActionButton extends MaterialComponent {
     transform: translateX(0);
     width: 56px;
     height: 56px;
-    background-color: #F44336;
+    background-color: ${Red[500]};
     color: white;
     border-radius: 28px;'''
   );

examples/fn/widgets/toolbar.dart

@@ -9,9 +9,9 @@ class Toolbar extends Component {
     align-items: center;
     height: 84px;
     z-index: 1;
-    background-color: #9C27B0; // Purple 500
+    background-color: ${Purple[500]};
     color: white;
-    box-shadow: 0 3px 6px rgba(0,0,0,0.16), 0 3px 6px rgba(0,0,0,0.23);'''
+    box-shadow: ${Shadow[2]};'''
   );
 
   Toolbar({String key, this.children}) : super(key: key);

examples/fn/widgets/widgets.dart

@@ -2,6 +2,8 @@ library widgets;
 
 import '../lib/fn.dart';
 import '../../../framework/fling-curve.dart';
+import '../../../framework/theme/colors.dart';
+import '../../../framework/theme/shadows.dart';
 import 'dart:collection';
 import 'dart:async';
 import 'dart:math' as math;

framework/theme/colors.dart

+// 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.
+
+const Map<int, String> Red = const {
+   50: '#FFEBEE',
+  100: '#FFCDD2',
+  200: '#EF9A9A',
+  300: '#E57373',
+  400: '#EF5350',
+  500: '#F44336',
+  600: '#E53935',
+  700: '#D32F2F',
+  800: '#C62828',
+  900: '#B71C1C',
+};
+
+const Map<int, String> Pink = const {
+   50: '#FCE4EC',
+  100: '#F8BBD0',
+  200: '#F48FB1',
+  300: '#F06292',
+  400: '#EC407A',
+  500: '#E91E63',
+  600: '#D81B60',
+  700: '#C2185B',
+  800: '#AD1457',
+  900: '#880E4F',
+};
+
+const Map<int, String> Purple = const {
+   50: '#F3E5F5',
+  100: '#E1BEE7',
+  200: '#CE93D8',
+  300: '#BA68C8',
+  400: '#AB47BC',
+  500: '#9C27B0',
+  600: '#8E24AA',
+  700: '#7B1FA2',
+  800: '#6A1B9A',
+  900: '#4A148C',
+};
+
+const Map<int, String> DeepPurple = const {
+   50: '#EDE7F6',
+  100: '#D1C4E9',
+  200: '#B39DDB',
+  300: '#9575CD',
+  400: '#7E57C2',
+  500: '#673AB7',
+  600: '#5E35B1',
+  700: '#512DA8',
+  800: '#4527A0',
+  900: '#311B92',
+};
+
+const Map<int, String> Indigo = const {
+   50: '#E8EAF6',
+  100: '#C5CAE9',
+  200: '#9FA8DA',
+  300: '#7986CB',
+  400: '#5C6BC0',
+  500: '#3F51B5',
+  600: '#3949AB',
+  700: '#303F9F',
+  800: '#283593',
+  900: '#1A237E',
+};
+
+const Map<int, String> Blue = const {
+   50: '#E3F2FD',
+  100: '#BBDEFB',
+  200: '#90CAF9',
+  300: '#64B5F6',
+  400: '#42A5F5',
+  500: '#2196F3',
+  600: '#1E88E5',
+  700: '#1976D2',
+  800: '#1565C0',
+  900: '#0D47A1',
+};
+
+const Map<int, String> LightBlue = const {
+   50: '#E1F5FE',
+  100: '#B3E5FC',
+  200: '#81D4FA',
+  300: '#4FC3F7',
+  400: '#29B6F6',
+  500: '#03A9F4',
+  600: '#039BE5',
+  700: '#0288D1',
+  800: '#0277BD',
+  900: '#01579B',
+};
+
+const Map<int, String> Cyan = const {
+   50: '#E0F7FA',
+  100: '#B2EBF2',
+  200: '#80DEEA',
+  300: '#4DD0E1',
+  400: '#26C6DA',
+  500: '#00BCD4',
+  600: '#00ACC1',
+  700: '#0097A7',
+  800: '#00838F',
+  900: '#006064',
+};
+
+const Map<int, String> Teal = const {
+   50: '#E0F2F1',
+  100: '#B2DFDB',
+  200: '#80CBC4',
+  300: '#4DB6AC',
+  400: '#26A69A',
+  500: '#009688',
+  600: '#00897B',
+  700: '#00796B',
+  800: '#00695C',
+  900: '#004D40',
+};
+
+const Map<int, String> Green = const {
+   50: '#E8F5E9',
+  100: '#C8E6C9',
+  200: '#A5D6A7',
+  300: '#81C784',
+  400: '#66BB6A',
+  500: '#4CAF50',
+  600: '#43A047',
+  700: '#388E3C',
+  800: '#2E7D32',
+  900: '#1B5E20',
+};
+
+const Map<int, String> LightGreen = const {
+   50: '#F1F8E9',
+  100: '#DCEDC8',
+  200: '#C5E1A5',
+  300: '#AED581',
+  400: '#9CCC65',
+  500: '#8BC34A',
+  600: '#7CB342',
+  700: '#689F38',
+  800: '#558B2F',
+  900: '#33691E',
+};
+
+const Map<int, String> Lime = const {
+   50: '#F9FBE7',
+  100: '#F0F4C3',
+  200: '#E6EE9C',
+  300: '#DCE775',
+  400: '#D4E157',
+  500: '#CDDC39',
+  600: '#C0CA33',
+  700: '#AFB42B',
+  800: '#9E9D24',
+  900: '#827717',
+};
+
+const Map<int, String> Yellow = const {
+   50: '#FFFDE7',
+  100: '#FFF9C4',
+  200: '#FFF59D',
+  300: '#FFF176',
+  400: '#FFEE58',
+  500: '#FFEB3B',
+  600: '#FDD835',
+  700: '#FBC02D',
+  800: '#F9A825',
+  900: '#F57F17',
+};
+
+const Map<int, String> Amber = const {
+   50: '#FFF8E1',
+  100: '#FFECB3',
+  200: '#FFE082',
+  300: '#FFD54F',
+  400: '#FFCA28',
+  500: '#FFC107',
+  600: '#FFB300',
+  700: '#FFA000',
+  800: '#FF8F00',
+  900: '#FF6F00',
+};
+
+const Map<int, String> Orange = const {
+   50: '#FFF3E0',
+  100: '#FFE0B2',
+  200: '#FFCC80',
+  300: '#FFB74D',
+  400: '#FFA726',
+  500: '#FF9800',
+  600: '#FB8C00',
+  700: '#F57C00',
+  800: '#EF6C00',
+  900: '#E65100',
+};
+
+const Map<int, String> DeepOrange = const {
+   50: '#FBE9E7',
+  100: '#FFCCBC',
+  200: '#FFAB91',
+  300: '#FF8A65',
+  400: '#FF7043',
+  500: '#FF5722',
+  600: '#F4511E',
+  700: '#E64A19',
+  800: '#D84315',
+  900: '#BF360C',
+};
+
+const Map<int, String> Brown = const {
+   50: '#EFEBE9',
+  100: '#D7CCC8',
+  200: '#BCAAA4',
+  300: '#A1887F',
+  400: '#8D6E63',
+  500: '#795548',
+  600: '#6D4C41',
+  700: '#5D4037',
+  800: '#4E342E',
+  900: '#3E2723',
+};
+
+const Map<int, String> Grey = const {
+   50: '#FAFAFA',
+  100: '#F5F5F5',
+  200: '#EEEEEE',
+  300: '#E0E0E0',
+  400: '#BDBDBD',
+  500: '#9E9E9E',
+  600: '#757575',
+  700: '#616161',
+  800: '#424242',
+  900: '#212121',
+};
+
+const Map<int, String> BlueGrey = const {
+   50: '#ECEFF1',
+  100: '#CFD8DC',
+  200: '#B0BEC5',
+  300: '#90A4AE',
+  400: '#78909C',
+  500: '#607D8B',
+  600: '#546E7A',
+  700: '#455A64',
+  800: '#37474F',
+  900: '#263238',
+};

framework/theme/shadows.dart

+// 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.
+
+const Map<int, String> Shadow = const {
+  1: '0  1px  3px rgba(0,0,0,0.12), 0  1px  2px rgba(0,0,0,0.24)',
+  2: '0  3px  6px rgba(0,0,0,0.16), 0  3px  6px rgba(0,0,0,0.23)',
+  3: '0 10px 20px rgba(0,0,0,0.19), 0  6px  6px rgba(0,0,0,0.23)',
+  4: '0 14px 28px rgba(0,0,0,0.25), 0 10px 10px rgba(0,0,0,0.22)',
+  5: '0 19px 38px rgba(0,0,0,0.30), 0 15px 12px rgba(0,0,0,0.22)',
+};