Add flutter_web samples (#75)

web/charts/flutter/lib/src/text_style.dart

@@ -0,0 +1,33 @@
+// Copyright 2018 the Charts project authors. Please see the AUTHORS file
+// for details.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import 'package:flutter_web_ui/ui.dart' show hashValues;
+import 'package:charts_common/common.dart' as common show Color, TextStyle;
+
+class TextStyle implements common.TextStyle {
+  int fontSize;
+  String fontFamily;
+  common.Color color;
+
+  @override
+  bool operator ==(Object other) =>
+      other is TextStyle &&
+      fontSize == other.fontSize &&
+      fontFamily == other.fontFamily &&
+      color == other.color;
+
+  @override
+  int get hashCode => hashValues(fontSize, fontFamily, color);
+}