`LayoutHandler.Windows`: Store children to a local variable

[MartyIX]

Description of Change

The PR trivially attempts to decrease the number of interops.

Issues Fixed

Contributes to #21787

[dotnet-policy-service[bot]]

Hey there @MartyIX! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[symbiogenesis]

Maybe we could write an analyzer to detect usages of iterating on members or properties that call platform-specific code.

[MartyIX]

It might generate a lot of false positives but it would be a nice tool to run it once in a while IMO.

[MartyIX]

@rmarinho Could you take a look please?

[MartyIX]

@jonathanpeppers Yes, here it is:

• Maui.Controls.Sample.Sandbox.exe_20240416_184241.speedscope.json - master
• Maui.Controls.Sample.Sandbox.exe_20240416_184416.speedscope.json - PR

[jonathanpeppers]

/azp run

[azure-pipelines[bot]]

Azure Pipelines successfully started running 3 pipeline(s).

[MartyIX]

Hm, it did not get merged automatically, or I don't understand how the feature work.