WebUI: Stop keypresses on the close icon from firing the Enter handler.

ui/webui/resources/cr_elements/cr_dialog/cr_dialog.js

Index: ui/webui/resources/cr_elements/cr_dialog/cr_dialog.js
diff --git a/ui/webui/resources/cr_elements/cr_dialog/cr_dialog.js b/ui/webui/resources/cr_elements/cr_dialog/cr_dialog.js
index 3e9fc20ba55944730342044421ecc1ec773b8336..8f73731a03640d9da601133819e39fb5ef104e83 100644
--- a/ui/webui/resources/cr_elements/cr_dialog/cr_dialog.js
+++ b/ui/webui/resources/cr_elements/cr_dialog/cr_dialog.js
@@ -147,6 +147,16 @@ Polymer({
     HTMLDialogElement.prototype.close.call(this, 'success');
   },
 
+  /**
+   * @private
+   * @param {Event} e
+   */
+  onCloseKeypress_: function(e) {
+    // Because the dialog may have a default Enter key handler, prevent
+    // keypress events from bubbling up from this element.
+    e.stopPropagation();
+  },
+
   /** @return {!PaperIconButtonElement} */
   getCloseButton: function() {
     return this.$.close;