Chrome Version: (copy from chrome://version)
OS: 58.0.3029.110 (Official Build) (64-bit)

What steps will reproduce the problem?
(1) Go to http://jsbin.com/xedudoyovi/edit?html,console,output

What is the expected result?

- The callback is run once as soon as `.observe()` is invoked, and it's run again when the parent element is removed from the DOM.

What happens instead?

- The callback is not run when the parent element is removed from the DOM.

Please use labels and text to provide additional information.


For graphics-related bugs, please copy/paste the contents of the about:gpu
page at the end of this report.