[geary/bug/728002-webkit2: 132/140] Really fix JS error calling ComposerWebView::save_selection.

[Michael Gratton <mjog src gnome org>]

commit 67762f22cb20506b026fedf608169cfed0bcfdac
Author: Michael James Gratton <mike vee net>
Date:   Mon Jan 30 15:40:58 2017 +1100

    Really fix JS error calling ComposerWebView::save_selection.
    
    * ui/composer-web-view.js: Increment must be in brackets.

 ui/composer-web-view.js |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/ui/composer-web-view.js b/ui/composer-web-view.js
index db75ca1..e52ec38 100644
--- a/ui/composer-web-view.js
+++ b/ui/composer-web-view.js
@@ -138,7 +138,7 @@ ComposerPageState.prototype = {
         this.checkCommandStack();
     },
     saveSelection: function() {
-        let id = ++this.nextSelectionId.toString();
+        let id = (++this.nextSelectionId).toString();
         this.selections.set(id, SelectionUtil.save());
         return id;
     },