fix(datepicker): stop propagation of esc in popup

- Stop propagation of esc key in datepicker popup, which can propagate to undesirable elements/handlers such as the modal

Closes #5074
Fixes #5013

src/datepicker/datepicker.js

@@ -746,6 +746,7 @@ function(scope, element, attrs, $compile, $parse, $document, $rootScope, $positi
 
   scope.keydown = function(evt) {
     if (evt.which === 27) {
+      evt.stopPropagation();
       scope.isOpen = false;
       element[0].focus();
     }