[FIX] website_sale: make eCommerce animations work in all browsers

The eCommerce sometimes animates product images when they are put in
the cart / wishlist / comparison panel. Those animations did not work
on Firefox and IE and made strange scrollbars appear instead.

addons/website_sale/static/src/css/website_sale.css

@@ -643,7 +643,7 @@ a.no-decoration {
 
 .o_website_sale_animate {
   opacity: 0.7;
-  position: absolute;
+  position: absolute !important;
   height: 150px;
   width: 150px;
   z-index: 1020;

addons/website_sale/static/src/css/website_sale.sass

@@ -567,7 +567,7 @@ a.no-decoration
 
 .o_website_sale_animate
     opacity: 0.7
-    position: absolute
+    position: absolute !important
     height: 150px
     width: 150px
     z-index: 1020