https://jsfiddle.net/472jdns0/4/ another example, blockquote should be removed and replaced by its content, but the output still have a blockquote shifted to the next sibling

This is an important issue, probably specific to insertHTML. Using formatblock for the moment, that behaves better

	formatBlock(value){ // improved formatBlock, toggle/unwrap content
		let currentValue = document.queryCommandValue('formatblock');
		if (value!==currentValue) return exec('formatblock', value);
		let block=sel.getRange().closest(currentValue||'*');
		while (block.contentEditable!=='true'&&block.parentNode.contentEditable!=='true'&&block.parentNode.childElementCount===1)
			block = block.parentNode;
		sel.setRange(sel.selectNode(block));
		exec('formatblock', 'div');
		
	}

Issue is reproducible on the latest canary(52.0.2730.0) and the latest stable(50.0.2661.94) on Windows-7, Mac OS 10.11.4 and Linux Ubuntu 14.04.

On older chrome version(30.0.1549.0) the above jsfiddles show followig result:

1. https://jsfiddle.net/472jdns0/3/

Output:
========= 
ioh	 2 2
i ,, h	 4 4 .
ok

foo bar 

2. https://jsfiddle.net/472jdns0/4/

Output:
========
      foo bar
thing


Marking this Untriaged and as non-regression issue for further investigation.

Thank you! 

Moving this nonessential bug to the next milestone.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

This issue has been moved once and is lower than Pri-1. Removing the milestone.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available. If you change it back, also remove the "Hotlist-Recharge-Cold" label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot