[geary] Fix message body quote button styling under WebKitGTK 2.20.

[Michael Gratton <mjog src gnome org>]

commit 3da72b2f76410cc0019e4f4f12ba751d8e3d36e5
Author: Michael James Gratton <mike vee net>
Date:   Wed Apr 11 14:00:15 2018 +1000

    Fix message body quote button styling under WebKitGTK 2.20.
    
    * ui/conversation-web-view.css: Replace bogus ">>" with simple descendent
      selector.

 ui/conversation-web-view.css |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/ui/conversation-web-view.css b/ui/conversation-web-view.css
index 81a4d1f..4480843 100644
--- a/ui/conversation-web-view.css
+++ b/ui/conversation-web-view.css
@@ -144,7 +144,7 @@ pre {
     display: block;
   }
 
-  .geary-quote-container >> .geary-button {
+  .geary-quote-container .geary-button {
     display: block;
     width: 100%;
     height: 16px;
@@ -174,7 +174,7 @@ pre {
     text-shadow: 0 1px rgba(255, 255, 255, 0.76923);
     box-shadow: inset 0 1px rgba(255, 255, 255, 0.8); }
   }
-  .geary-quote-container >> .geary-button:hover {
+  .geary-quote-container .geary-button:hover {
     /* Likewise the properties below also workaround WK Bug 166648,
      * and taken from gtk/theme/Adwaita/gtk-contained.css. */
     color: #2e3436;