Currently, we dispatch keypress event when Enter is pressed without
modifiers or only with the Shift key (line break).
However, other browsers dispatch keypress events for Ctrl + Enter also
even if it doesn't cause any text input.
So, we should fire keypress events for Ctrl + Enter, even in strict
keypress dispatching mode. Note that with other modifiers, it depends on
the browser and/or platform and we can't dispatch the event for
consistent behavior.
This means web developers shouldn't rely one keypress events to catch
Alt + Enter, Meta + Enter and two or more modifiers + Enter.
Based on BZ 1438133
Resolves#2161
