Let Node.textContent never throw

Let Node.textContent never throw

http://dom.spec.whatwg.org/#dom-node-textcontent

This is per the spec. The only case where it could previously have
thrown is if ContainerNode::checkAcceptChild returned false. I could
not find a situation where that would have happened, so just assert
that the internal appendChild call does not throw an exception.

BUG=326133
TEST=none

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=163275

[jochen (gone - plz use gerrit), 2013-12-05 14:23:44]

lgtm

[commit-bot: I haz the power, 2013-12-05 14:26:40]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/philipj@opera.com/106503002/1

[commit-bot: I haz the power, 2013-12-05 16:34:18]

Commit queue rejected this change because the description was changed
between the time the change entered the commit queue and the time it
was ready to commit. You can safely check the commit box again.

[commit-bot: I haz the power, 2013-12-05 16:46:05]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/philipj@opera.com/106503002/1

[commit-bot: I haz the power, 2013-12-05 16:46:23]

Change committed as 163275