baseIcon: Always recreate icon texture on style changes

Commit 26580f8f reintroduced an optimization on style changes to avoid
creating icons unconditionally. As this breaks icon theme changes (for
instance when toggling "High Contrast" in the universal access menu),
remove it again.

https://bugzilla.gnome.org/show_bug.cgi?id=672941

js/ui/iconGrid.js

@@ -146,11 +146,6 @@ const BaseIcon = new Lang.Class({
             size = found ? len : ICON_SIZE;
         }
 
-        // don't create icons unnecessarily
-        if (size == this.iconSize &&
-            this._iconBin.child)
-            return;
-
         this._createIconTexture(size);
     }
 });