UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 Safari/537.36

Steps to reproduce the problem:
1.  From the Terminal, start headless mode using either latest Stable or Chrome Canary:

cd /Applications/Google Chrome Canary.app/Contents/MacOS
./Google\ Chrome\ Canary --disable-gpu --headless --remote-debugging-port=9222 https://www.w3schools.com/tags/tryit.asp?filename=tryhtml_form_submit

2. In regular Chrome, go to http://localhost:9222

3. Click on the "Tryit Editor v3.5" link.

4. Click on the FirstName field, i.e. where it contains the work "Mickey".  The field will get a blue highlight around it to indicate it has focus.  Type in a character to verify that the field has focus.

5. Press the 'tab' key.  The focus and blue highlight will shift to the "Last name:" field, and the word "Mouse" will get auto-selected.

6. Start typing in characters to attempt to change the value from "Mouse" to something else.

Note that the field doesn't change.  You have to click the mouse on the "Last name:" field in order to change it's value.

What is the expected behavior?
The field that seems to have focus - "Last name:" - should be the field that accepts the user input.

What went wrong?
Pressing 'tab' seems to change the field that has the focus and give another field keyboard focus, but it doesn't actually give the new field focus.

Did this work before? No 

Chrome version: 61.0.3163.100  Channel: stable
OS Version: OS X 10.12.6
Flash Version: