DevTools: [Elements] Fix updates of the DOM tree upon inline text node removal

A tree item title was not updated if it had a single inline child text node.

R=vsevik

Review URL: https://codereview.chromium.org/705263002

git-svn-id: svn://svn.chromium.org/blink/trunk@184982 bbb929c8-8fbe-4397-9dbb-9b2b20218538