Chrome: 71.0.3354.0 DEV

Steps to repro:
# Enable Chromevox with ctrl+alt+z
# Open file manager with alt+shift+m
# Navigate to a folder with files and navigate to the 3rd or 4th file
# Hold down shift and press down arrow to select two files
# Notice that Chromevox reads the filename as you shift+arrow

Expected: Chromevox would say 'selected: <filename>'

Actual: Chromevox users have no indication that selection is happening.