TinyMCE wpView: add sandbox iframe body styling to get proper height when resizing the iframe, fixes #29270.
Built from https://develop.svn.wordpress.org/trunk@29544


git-svn-id: http://core.svn.wordpress.org/trunk@29320 1a063a9b-81f0-0310-95a4-ce76da25c4cd
TinyMCE wpView: scale iframes to 100% width and ensure they have transparent background. See #29048.
Built from https://develop.svn.wordpress.org/trunk@29545


git-svn-id: http://core.svn.wordpress.org/trunk@29321 1a063a9b-81f0-0310-95a4-ce76da25c4cd