Skip flaky test on Firefox (#180941)

Skips flaky test on Firefox until
flutter/flutter#180940 is fixed.

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we expect every widget to implement].
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[test-exempt].
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---------

Co-authored-by: Mouad Debbar <mouad.debbar@gmail.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: 3 people

engine/src/flutter/lib/web_ui/test/engine/view_embedder/style_manager_test.dart

@@ -15,23 +15,29 @@ void main() {
 
 void doTests() {
   group('StyleManager', () {
-    test('attachGlobalStyles hides the outline when focused', () {
-      final DomElement flutterViewElement = createDomElement(DomManager.flutterViewTagName);
+    test(
+      'attachGlobalStyles hides the outline when focused',
+      () {
+        final DomElement flutterViewElement = createDomElement(DomManager.flutterViewTagName);
 
-      domDocument.body!.append(flutterViewElement);
-      StyleManager.attachGlobalStyles(
-        node: flutterViewElement,
-        styleId: 'testing',
-        styleNonce: 'testing',
-        cssSelectorPrefix: DomManager.flutterViewTagName,
-      );
-      final expected = ui_web.browser.browserEngine == ui_web.BrowserEngine.firefox
-          ? 'rgb(0, 0, 0) 0px'
-          : 'rgb(0, 0, 0) none 0px';
-      final String got = domWindow.getComputedStyle(flutterViewElement, 'focus').outline;
+        domDocument.body!.append(flutterViewElement);
+        StyleManager.attachGlobalStyles(
+          node: flutterViewElement,
+          styleId: 'testing',
+          styleNonce: 'testing',
+          cssSelectorPrefix: DomManager.flutterViewTagName,
+        );
+        final expected = ui_web.browser.browserEngine == ui_web.BrowserEngine.firefox
+            ? 'rgb(0, 0, 0) 0px'
+            : 'rgb(0, 0, 0) none 0px';
+        final String got = domWindow.getComputedStyle(flutterViewElement, 'focus').outline;
 
-      expect(got, expected);
-    });
+        expect(got, expected);
+      },
+      skip: isFirefox
+          ? 'Skip until we fix the flake on Firefox. See: https://github.com/flutter/flutter/issues/180940'
+          : null,
+    );
 
     test('styleSceneHost', () {
       expect(() => StyleManager.styleSceneHost(createDomHTMLDivElement()), throwsAssertionError);