Use "children insertion steps" for script

[noamr]

This fixes a regression where script would be run as a result of child removal/mutation. Together with whatwg/dom#1460

Closes #12279

• At least two implementers are interested (and none opposed):
  • This is already implemented and was in the spec before
• Tests are written and can be reviewed and commented upon at:
  • https://wpt.fyi/results/dom/nodes/insertion-removing-steps/script-does-not-run-on-child-removal.window.html?label=master&label=experimental&aligned&q=script-does-not-run-on-child-removal
• Implementation bugs are filed:
  • N/A

(See WHATWG Working Mode: Changes for more details.)

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/infrastructure.html ( diff )
/scripting.html ( diff )

[annevk]

I realize this matches Chromium and WebKit, but this seems like very strange behavior. Changing a Text node from "foo" to "bar" or "foobar" would not trigger this, but appending a Text node would.

Also, the template here is incorrect, right? @shannonbooth said that Firefox has different behavior.

cc @smaug---- @rniwa @domfarolino