I can confirm that with the same version of Chrome, I could use keyboard shortcuts fine with Stretch's ibus 1.5.14-3 but no longer can with 1.5.19-1: I have to click out of text input fields in order for shortcuts like CTRL-T to work as expected.
There was <https://github.com/ibus/ibus/issues/2073> about this, but it's currently closed. -- Stéphane Lavergne