Compare KeyCodes using KeyCode.equals
Compare KeyCodes using KeyCode.equals

A few keybindings don't work currently, at least on my Linux desktop.
An example is the new file dialog.  We would expect escape to close the
dialog, and enter to validate.

The problem is that the callback in widget.ts:addKeyListener uses === to
test equality of two KeyCodes.  However, this checks if the two objects
are the same instance, which is not necessarily the case.  Change it to
KeyCode.equals.

Fixes #1007

Signed-off-by: Simon Marchi <fa7054fed17d58b06d3b1bf9b1077e42165a09ec@ericsson.com>

epatpol/theia-1,epatpol/theia-1,epatpol/theia-1