Close modals with esc or backspace

js/id/ui/modal.js

@@ -1,6 +1,13 @@
 iD.ui.modal = function(blocking) {
+
     var animate = d3.select('div.modal').empty();
 
+    var keybinding = d3.keybinding('modal')
+        .on('⌫', close)
+        .on('⎋', close);
+
+    d3.select(document).call(keybinding);
+
     d3.select('div.modal').transition()
         .style('opacity', 0).remove();
 
@@ -30,5 +37,10 @@ iD.ui.modal = function(blocking) {
         shaded.style('opacity', 1);
     }
 
+    function close() {
+        shaded.remove();
+        keybinding.off();
+    }
+
     return shaded;
 };