Bug 1733938: Allow 'ESC' key to cancel adding of a block

When on the 'add block' popup

behatnotneeded

Change-Id: I8bb59e9bedd5a64e6b59330aa5e2fc2aba3ef639
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>

htdocs/js/views.js

@@ -995,7 +995,7 @@
     function setupPositionBlockDialog() {
 
         $('#addblock .cancel, #addblock .deletebutton').on('mousedown keydown', function(e) {
-            if (isHit(e)) {
+            if (isHit(e) || e.keyCode === $j.ui.keyCode.ESCAPE) {
                 closePositionBlockDialog(e, {'saved': false});
             }
         });