[gnome-maps] osmEditDialog: Don't add Address to popover if already added

[Marcus Lundblad <mlundblad src gnome org>]

commit 8a8a7ea2d4f52028c82ec3e9fa685ffaea801f7e
Author: Marcus Lundblad <ml update uu se>
Date:   Sun Aug 20 22:57:04 2017 +0200

    osmEditDialog: Don't add Address to popover if already added
    
    Use !== null to check if any subtags under address is already included
    (including placeholder empty strings).
    
    https://bugzilla.gnome.org/show_bug.cgi?id=786551

 src/osmEditDialog.js |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/osmEditDialog.js b/src/osmEditDialog.js
index 190f714..ea2ce93 100644
--- a/src/osmEditDialog.js
+++ b/src/osmEditDialog.js
@@ -750,7 +750,7 @@ const OSMEditDialog = new Lang.Class({
 
             if (fieldSpec.subtags) {
                 fieldSpec.subtags.forEach((function(tag) {
-                    if (this._osmObject.get_tag(tag))
+                    if (this._osmObject.get_tag(tag) !== null)
                         hasValue = true;
                 }).bind(this));
             } else {