Flutter upgrade

lib/src/widgets/trail_button.dart

@@ -2,11 +2,14 @@ import 'package:flutter/material.dart';
 import 'package:cake_wallet/palette.dart';
 
 class TrailButton extends StatelessWidget {
-  TrailButton({@required this.caption, this.textColor, @required this.onPressed});
+  TrailButton({
+    required this.caption,
+    required this.onPressed,
+    this.textColor});
 
   final String caption;
   final VoidCallback onPressed;
-  final Color textColor;
+  final Color? textColor;
 
   @override
   Widget build(BuildContext context) {
@@ -14,13 +17,14 @@ class TrailButton extends StatelessWidget {
       minWidth: double.minPositive,
       highlightColor: Colors.transparent,
       splashColor: Colors.transparent,
-      child: FlatButton(
-          padding: EdgeInsets.all(0),
+      child: TextButton(
+          // FIX-ME: ignored padding
+          //padding: EdgeInsets.all(0),
           child: Text(
             caption,
             style: TextStyle(
                 color: textColor ??
-                    Theme.of(context).accentTextTheme.display4.decorationColor,
+                    Theme.of(context).accentTextTheme!.headline1!.decorationColor!,
                 fontWeight: FontWeight.w600,
                 fontSize: 14),
           ),