[geary] Fix 0px elements being rendered as 1px boxes.

[Michael Gratton <mjog src gnome org>]

commit 8f756cdbbd956a8111630e7b019d32832139cdde
Author: Michael James Gratton <mike vee net>
Date:   Sun Aug 14 13:38:26 2016 +1000

    Fix 0px elements being rendered as 1px boxes.

 .../conversation-viewer/conversation-viewer.vala   |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/src/client/conversation-viewer/conversation-viewer.vala 
b/src/client/conversation-viewer/conversation-viewer.vala
index 7cac33d..a563319 100644
--- a/src/client/conversation-viewer/conversation-viewer.vala
+++ b/src/client/conversation-viewer/conversation-viewer.vala
@@ -1525,7 +1525,11 @@ public class ConversationViewer : Gtk.Box {
                         continue;
                     
                     string src = element.get_attribute("src");
-                    if (!web_view.is_always_loaded(src)) {
+                    // Don't prefix empty src strings since it will
+                    // cause e.g. 0px images (commonly found in
+                    // commercial mailouts) to be rendered as broken
+                    // images instead of empty elements.
+                    if (src.length > 0 && !web_view.is_always_loaded(src)) {
                         // Workaround a WebKitGTK+ 2.4.10 crash. See Bug 763933
                         element.remove_attribute("src");
                         element.set_attribute("src", web_view.allow_prefix + src);