chore(webkit): polyfill `PublicKeyCredential` (#35702)

packages/playwright-core/src/server/webkit/wkPage.ts

@@ -781,10 +781,33 @@ export class WKPage implements PageDelegate {
     }
     scripts.push('if (!window.safari) window.safari = { pushNotification: { toString() { return "[object SafariRemoteNotification]"; } } };');
     scripts.push('if (!window.GestureEvent) window.GestureEvent = function GestureEvent() {};');
+    scripts.push(this._publicKeyCredentialScript());
     scripts.push(...this._page.allInitScripts().map(script => script.source));
     return scripts.join(';\n');
   }
 
+  private _publicKeyCredentialScript(): string {
+    function polyfill() {
+      /**
+       * Some sites don't check existance of PublicKeyCredentials because all browsers except Webkit on Linux implement it.
+       * We polyfill the subset that's used for feature detection, so that login flows that'd work in Safari don't crash with "PublicKeyCredential is not defined" in CI.
+       * https://developer.mozilla.org/en-US/docs/Web/API/PublicKeyCredential
+       */
+      window.PublicKeyCredential ??= {
+        async getClientCapabilities() {
+          return {};
+        },
+        async isConditionalMediationAvailable() {
+          return false;
+        },
+        async isUserVerifyingPlatformAuthenticatorAvailable() {
+          return false;
+        },
+      } as any;
+    }
+    return `(${polyfill.toString()})();`;
+  }
+
   async _updateBootstrapScript(): Promise<void> {
     await this._updateState('Page.setBootstrapScript', { source: this._calculateBootstrapScript() });
   }

tests/library/capabilities.spec.ts

@@ -480,3 +480,17 @@ it('should not auto play audio', {
   await page.goto('http://127.0.0.1/audio.html');
   await expect(page.locator('#log')).toHaveText('State: suspended');
 });
+
+it('should not crash on feature detection for PublicKeyCredential', {
+  annotation: {
+    type: 'issue',
+    description: 'https://github.com/microsoft/playwright/issues/35433'
+  }
+}, async ({ page, server }) => {
+  await page.goto(server.EMPTY_PAGE);
+  await page.evaluate(async () => {
+    await PublicKeyCredential.getClientCapabilities();
+    await PublicKeyCredential.isConditionalMediationAvailable();
+    await PublicKeyCredential.isUserVerifyingPlatformAuthenticatorAvailable();
+  });
+});

tests/library/modernizr.spec.ts

@@ -55,7 +55,6 @@ it('Safari Desktop', async ({ browser, browserName, platform, server, headless }
 
   if (platform === 'linux') {
     expected.speechrecognition = false;
-    expected.publickeycredential = false;
     expected.mediastream = false;
     if (headless)
       expected.todataurlwebp = true;
@@ -118,7 +117,6 @@ it('Mobile Safari', async ({ playwright, browser, browserName, platform, server,
 
   if (platform === 'linux') {
     expected.speechrecognition = false;
-    expected.publickeycredential = false;
     expected.mediastream = false;
     if (headless)
       expected.todataurlwebp = true;