fix(expansion-panel): inconsistent margin for nested panels (#11305)
fix(expansion-panel): inconsistent margin for nested panels (#11305)

Fixes some inconsistent margin when expansion panels are nested inside other expansion panels.

Fixes #11254.
amcdnl/material2,andrewseguin/material2,amcdnl/material2,DevVersion/material2,andrewseguin/material2,DevVersion/material2,jelbourn/material2,crisbeto/material2,DevVersion/material2,jelbourn/material2,Jefiozie/material2,jelbourn/material2,ppham27/material2,andrewseguin/material2,angular/components,amcdnl/material2,mmalerba/material2,DevVersion/material2,crisbeto/material2,angular/components,ppham27/material2,Jefiozie/material2,crisbeto/material2,josephperrott/material2,Jefiozie/material2,amcdnl/material2,ppham27/material2,mmalerba/material2,mmalerba/material2,crisbeto/material2,josephperrott/material2,josephperrott/material2,mmalerba/material2,angular/components,angular/components,Jefiozie/material2,jelbourn/material2,andrewseguin/material2,amcdnl/material2,mmalerba/material2,Jefiozie/material2,DevVersion/material2,ppham27/material2,jelbourn/material2,josephperrott/material2,andrewseguin/material2,josephperrott/material2,ppham27/material2