fix(tree): theming nested notes (#12938)
fix(tree): theming nested notes (#12938)

changes nested-tree-nodes to be styled the same as tree-nodes
andrewseguin/material2,jelbourn/material2,josephperrott/material2,crisbeto/material2,andrewseguin/material2,josephperrott/material2,jelbourn/material2,Jefiozie/material2,angular/components,angular/components,josephperrott/material2,DevVersion/material2,DevVersion/material2,mmalerba/material2,angular/components,Jefiozie/material2,DevVersion/material2,Jefiozie/material2,andrewseguin/material2,josephperrott/material2,andrewseguin/material2,crisbeto/material2,mmalerba/material2,DevVersion/material2,andrewseguin/material2,Jefiozie/material2,mmalerba/material2,jelbourn/material2,Jefiozie/material2,DevVersion/material2,mmalerba/material2,angular/components,mmalerba/material2,crisbeto/material2,crisbeto/material2,jelbourn/material2,jelbourn/material2,josephperrott/material2