test [nfc]: Unmark testFoo functions as async

Discovered while testing out `discarded_futures` for #731.

Related: #731

Author: chrisbobbe

test/widgets/emoji_reaction_test.dart

@@ -146,12 +146,12 @@ void main() {
       for (final emojiset in [Emojiset.text, Emojiset.google]) {
         for (final textDirection in TextDirection.values) {
           for (final textScaleFactor in kTextScaleFactors) {
-            Future<void> runSmokeTest(
+            void runSmokeTest(
               String description,
               List<Reaction> reactions, {
               required List<User> users,
               required Map<String, RealmEmojiItem> realmEmoji,
-            }) async {
+            }) {
               final descriptionDetails = [
                 displayEmojiReactionUsers ? 'show names when few' : 'no names',
                 emojiset.name,

test/widgets/text_test.dart

@@ -88,13 +88,13 @@ void main() {
   });
 
   group('weightVariableTextStyle', () {
-    Future<void> testWeights(
+    void testWeights(
       String description, {
       required TextStyle Function(BuildContext context) styleBuilder,
       bool platformRequestsBold = false,
       required List<FontVariation> expectedFontVariations,
       required FontWeight expectedFontWeight,
-    }) async {
+    }) {
       testWidgets(description, (tester) async {
         addTearDown(testBinding.reset);
         tester.platformDispatcher.accessibilityFeaturesTestValue =
@@ -179,13 +179,13 @@ void main() {
   });
 
   group('bolderWghtTextStyle', () {
-    Future<void> testBolderWghtTextStyle(
+    void testBolderWghtTextStyle(
       String description, {
       required TextStyle Function(BuildContext context) makeStyle,
       bool platformRequestsBold = false,
       required double expectedWght,
       required FontWeight expectedFontWeight,
-    }) async {
+    }) {
       testWidgets(description, (tester) async {
         addTearDown(testBinding.reset);
         tester.platformDispatcher.accessibilityFeaturesTestValue =
@@ -340,12 +340,12 @@ void main() {
   });
 
   group('proportionalLetterSpacing', () {
-    Future<void> testLetterSpacing(
+    void testLetterSpacing(
       String description, {
       required double Function(BuildContext context) getValue,
       double? ambientTextScaleFactor,
       required double expected,
-    }) async {
+    }) {
       testWidgets(description, (tester) async {
         addTearDown(testBinding.reset);
         if (ambientTextScaleFactor != null) {
@@ -394,7 +394,7 @@ void main() {
   });
 
   group('localizedTextBaseline', () {
-    Future<void> testLocalizedTextBaseline(Locale locale, TextBaseline expected) async {
+    void testLocalizedTextBaseline(Locale locale, TextBaseline expected) {
       testWidgets('gives $expected for $locale', (tester) async {
         addTearDown(testBinding.reset);
         tester.platformDispatcher.localeTestValue = locale;

test/widgets/theme_test.dart

@@ -22,11 +22,11 @@ void main() {
   group('button text size and letter spacing', () {
     const buttonText = 'Zulip';
 
-    Future<void> doCheck(
+    void doCheck(
       String description, {
       required Widget button,
       double? ambientTextScaleFactor,
-    }) async {
+    }) {
       testWidgets(description, (tester) async {
         addTearDown(testBinding.reset);
         if (ambientTextScaleFactor != null) {