[Linux] Fix high CPU consumption

[huanghongxun]

This PR fixes flutter/flutter#77710.

The high CPU consumption is caused by reordering GdkWindows in draw function, which will schedule redraw of entire GtkWindow later, leading to a 'dead loop'.

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
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• I listed at least one issue that this PR fixes in the description above.
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  writing and running engine tests.
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• All existing and new tests are passing.
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[flutter-dashboard]

It looks like this pull request may not have tests. Please make sure to add tests before merging. If you need an exemption to this rule, contact Hixie on the #hackers channel in Chat.

If you are not sure if you need tests, consider this rule of thumb: the purpose of a test is to make sure someone doesn't accidentally revert the fix. Ask yourself, is there anything in your PR that you feel it is important we not accidentally revert back to how it was before your fix?

Reviewers: Read the Tree Hygiene page and make sure this patch meets those guidelines before LGTMing.

[huanghongxun]

@wmww @robert-ancell

[cbracken]