Fixes:
- Parsing of blocks in the second half of post_content.
- Outputting malformed HTML when `the_content( null, true )` or `<!--noteaser-->` is used.
Props lukecarbis, garrett-eclipse, birgire.
Fixes#46471.
git-svn-id: https://develop.svn.wordpress.org/trunk@45261 602fd350-edb4-49c9-b593-d223f7449a82