Close the page in the text layer caret selection integration test

[timvandermeij]

This integration test is currently the only one that spawns a separate browser instance. However, while it closes the browser once it's done, it doesn't close the page (and therefore doesn't call the testingClose method) like the other integration tests do.

This commit fixes this difference by closing the page before closing the browser, thereby ensuring all regular cleanup logic gets called and we avoid (intermittent) shutdown tracebacks in the logs. This allows upcoming integration tests that spawn a separate browser instance to reuse this pattern to cleanly end the test.

Given that we integrate the closeSinglePage code from #17962 for this patch, @calixteman is credited as the co-author.

[timvandermeij]

/botio test

[moz-tools-bot]

From: Bot.io (Linux m4)

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Received

Command cmd_test from @timvandermeij received. Current queue size: 0

Live output at: http://54.241.84.105:8877/ef2d91320447d63/output.txt

[moz-tools-bot]

From: Bot.io (Windows)

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Received

Command cmd_test from @timvandermeij received. Current queue size: 0

Live output at: http://54.193.163.58:8877/82a64abe6bc496e/output.txt

[moz-tools-bot]

From: Bot.io (Linux m4)

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Failed

Full output at http://54.241.84.105:8877/ef2d91320447d63/output.txt

Total script time: 29.22 mins

• Unit tests: Passed
• Integration Tests: Passed
• Regression tests: FAILED

  different ref/snapshot: 17
  different first/second rendering: 2

Image differences available at: http://54.241.84.105:8877/ef2d91320447d63/reftest-analyzer.html#web=eq.log

[moz-tools-bot]

From: Bot.io (Windows)

---

Failed

Full output at http://54.193.163.58:8877/82a64abe6bc496e/output.txt

Total script time: 44.49 mins

• Unit tests: Passed
• Integration Tests: Passed
• Regression tests: FAILED

  different ref/snapshot: 5

Image differences available at: http://54.193.163.58:8877/82a64abe6bc496e/reftest-analyzer.html#web=eq.log