Accepting completions was not working as expected when there is only one
inline suggestion (and the suggestion box is not being shown). For
instance for a property like "flex-grow" if user types "flex-g" (there
is only one suggestion), pressing tab at this point, did not accept the
entire suggestion "flex-grow"

Bug: 524131115
Change-Id: I2eb69d4f78a428965d927df51a06d0d5c13fd8f1
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/7966040
Auto-Submit: Samiya Caur <samiyac@chromium.org>
Commit-Queue: Samiya Caur <samiyac@chromium.org>
Reviewed-by: Jack Franklin <jacktfranklin@chromium.org>