fix(Playwright): switchTo resolves nested iframes relative to current frame (#5717)

switchTo() always built the frame locator from the page, so switching into
an iframe nested inside the current frame silently resolved to nothing:
the step passed, but every following action timed out and no element on
any level was reachable.

The existence check ahead of it runs against the current frame, which is
why the bad switch was never reported. Chain the frame locator from the
current frame when there is one, as 3.x did.

frameLocator() is synchronous, so the Promise.race wrapper never raced
anything and left a dangling 5s timer behind on every switchTo call.

Fixes #5688


Claude-Session: https://claude.ai/code/session_01M93h8jjpyUt1A7Px3kwpxC

Co-authored-by: DavertMik <davert@testomat.io>
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: 3 people

lib/helper/Playwright.js

@@ -3667,8 +3667,7 @@ class Playwright extends Helper {
     }
 
     try {
-      // Always create frame locator from page to avoid nested frame paths
-      this.frame = await Promise.race([this.page.frameLocator(locator), new Promise((_, reject) => setTimeout(() => reject(new Error('Frame locator timeout')), 5000))])
+      this.frame = this.frame ? this.frame.frameLocator(locator) : this.page.frameLocator(locator)
     } catch (e) {
       console.warn('Warning during frame locator creation:', e.message)
       throw new Error(`Frame ${JSON.stringify(locator)} could not be accessed`)

test/helper/webapi.js

@@ -1963,6 +1963,38 @@ export function tests() {
     })
   })
 
+  describe('#switchTo', () => {
+    beforeEach(function () {
+      if (isHelper('CDPBrowser')) this.skip() // switchTo/iframes are not implemented in CDPBrowser
+    })
+
+    it('should switch to nested iframes one by one', async () => {
+      await I.amOnPage('/iframe_nested')
+      await I.switchTo('[name=wrapper]')
+      await I.see('Iframe test')
+      await I.switchTo('[name=content]')
+      await I.see('Information')
+      await I.see('Lots of valuable data here')
+    })
+
+    it('should return to the top level context from a nested iframe', async () => {
+      await I.amOnPage('/iframe_nested')
+      await I.switchTo('[name=wrapper]')
+      await I.switchTo('[name=content]')
+      await I.see('Information')
+      await I.switchTo(null)
+      await I.see('Nested Iframe test')
+    })
+
+    it('should not find a nested iframe from the top level context', async () => {
+      await I.amOnPage('/iframe_nested')
+      await I.switchTo('[name=content]').then(
+        () => assert.fail('switched to an iframe which is not in the current context'),
+        err => assert.include(err.message, 'was not found'),
+      )
+    })
+  })
+
   describe('scroll: #scrollTo, #scrollPageToTop, #scrollPageToBottom', () => {
     beforeEach(function () {
       if (I.capabilities?.layout === 'none') this.skip() // scrolling requires a real layout engine