[epiphany/mcatanzaro/#985] Remove unused EphyMiddleClickableButton

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 3a97b3a1511263a976d997fb58ef31ec7307f22a
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Tue Nov 5 16:35:55 2019 -0600

    Remove unused EphyMiddleClickableButton
    
    Fixes #985

 lib/widgets/ephy-middle-clickable-button.c | 72 ------------------------------
 lib/widgets/ephy-middle-clickable-button.h | 34 --------------
 lib/widgets/meson.build                    |  1 -
 3 files changed, 107 deletions(-)
---
diff --git a/lib/widgets/meson.build b/lib/widgets/meson.build
index cea7788a7..217b871fc 100644
--- a/lib/widgets/meson.build
+++ b/lib/widgets/meson.build
@@ -14,7 +14,6 @@ libephywidgets_sources = [
   'ephy-download-widget.c',
   'ephy-file-chooser.c',
   'ephy-location-entry.c',
-  'ephy-middle-clickable-button.c',
   'ephy-security-popover.c',
   'ephy-title-box.c',
   'ephy-title-widget.c',