fix(layout): fix 'layout-padding'

[TheHippo]

make sure css properties of layout-padding are applied correctly to elements with 'layout-padding' and 'flex' elements below

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[gkalpak]

This is essentially a duplicate of #939.

[TheHippo]

You are correct. I had a private repository before submitting and didn't checked with the existing pull requests.
Sorry for the duplication.
At least it is a sign this is a issue bothering more people.

[googlebot]

CLAs look good, thanks!

[ajoslin]

Merged, thanks.