TextFormField/TextField - remove spaces in character counter (#18096)

* TextFormField/TextField - remove spaces in character counter(follow material design guidelines)

packages/flutter/lib/src/material/text_field.dart

@@ -317,7 +317,7 @@ class _TextFieldState extends State<TextField> with AutomaticKeepAliveClientMixi
     if (!needsCounter)
       return effectiveDecoration;
 
-    final String counterText = '${_effectiveController.value.text.runes.length} / ${widget.maxLength}';
+    final String counterText = '${_effectiveController.value.text.runes.length}/${widget.maxLength}';
     if (_effectiveController.value.text.runes.length > widget.maxLength) {
       final ThemeData themeData = Theme.of(context);
       return effectiveDecoration.copyWith(

packages/flutter/test/material/text_field_test.dart

@@ -1620,16 +1620,16 @@ void main() {
     await tester.pump();
 
     expect(textController.text, '0123456789101112');
-    expect(find.text('16 / 10'), findsOneWidget);
-    Text counterTextWidget = tester.widget(find.text('16 / 10'));
+    expect(find.text('16/10'), findsOneWidget);
+    Text counterTextWidget = tester.widget(find.text('16/10'));
     expect(counterTextWidget.style.color, equals(Colors.deepPurpleAccent));
 
     await tester.enterText(find.byType(TextField), '0123456789');
     await tester.pump();
 
     expect(textController.text, '0123456789');
-    expect(find.text('10 / 10'), findsOneWidget);
-    counterTextWidget = tester.widget(find.text('10 / 10'));
+    expect(find.text('10/10'), findsOneWidget);
+    counterTextWidget = tester.widget(find.text('10/10'));
     expect(counterTextWidget.style.color, isNot(equals(Colors.deepPurpleAccent)));
   });
 
@@ -1647,12 +1647,12 @@ void main() {
       ),
     ));
 
-    expect(find.text('0 / 10'), findsOneWidget);
+    expect(find.text('0/10'), findsOneWidget);
 
     await tester.enterText(find.byType(TextField), '01234');
     await tester.pump();
 
-    expect(find.text('5 / 10'), findsOneWidget);
+    expect(find.text('5/10'), findsOneWidget);
   });
 
   testWidgets('TextField identifies as text field in semantics', (WidgetTester tester) async {