Implement a floating action button in fn

sky/examples/fn/widgets/floating_action_button.dart

Index: sky/examples/fn/widgets/floating_action_button.dart
diff --git a/sky/examples/fn/widgets/floating_action_button.dart b/sky/examples/fn/widgets/floating_action_button.dart
new file mode 100644
index 0000000000000000000000000000000000000000..d40e74cf313c2688e4f85e5b83541ab77443d671
--- /dev/null
+++ b/sky/examples/fn/widgets/floating_action_button.dart
@@ -0,0 +1,22 @@
+part of widgets;
+
+class FloatingActionButton extends StyleComponent {
+  static final Style _style = new Style('''
+    position: absolute;
+    display: flex;
+    justify-content: center;
+    align-items: center;
+    bottom: 16px;
+    right: 16px;
+    width: 56px;
+    height: 56px;
+    background-color: #F44336;
+    color: white;
+    border-radius: 28px;
+    box-shadow: 0 10px 20px rgba(0,0,0,0.19), 0 6px 6px rgba(0,0,0,0.23);'''
+  );
+
+  Style get style => _style;
+
+  FloatingActionButton({ Object key, Node content }) : super(key: key, content: content);
+}