Add PiP and play icons as gresource

Add missing PiP icons from web devel kit. Also add play/pause
icons at the right size and remove all workarounds/scaling
implemented or these two.

Playback icons are always two bars for pause and triangle for play,
so hopefully this will not be problematic, as this guaranties the
right size for them that Adwaita unfortunately cannot provide.

src/headerbarBase.js

@@ -23,7 +23,6 @@ class ClapperHeaderBarBase extends Gtk.Box
 
         this.isMaximized = false;
         this.isMenuOnLeft = true;
-        this.hasPipIcons = false;
 
         const uiBuilder = Misc.getBuilderForName('clapper.ui');
 
@@ -53,7 +52,7 @@ class ClapperHeaderBarBase extends Gtk.Box
         this.extraButtonsBox.add_css_class('linked');
 
         const floatButton = new Gtk.Button({
-            icon_name: 'go-bottom-symbolic',
+            icon_name: 'pip-in-symbolic',
             can_focus: false,
         });
         floatButton.add_css_class('osd');
@@ -221,9 +220,7 @@ class ClapperHeaderBarBase extends Gtk.Box
         const floatButton = this.extraButtonsBox.get_first_child();
         if(!floatButton) return;
 
-        const iconName = (!this.hasPipIcons)
-            ? 'go-bottom-symbolic'
-            : (isFloating)
+        const iconName = (isFloating)
             ? 'pip-out-symbolic'
             : 'pip-in-symbolic';
 
@@ -242,15 +239,6 @@ class ClapperHeaderBarBase extends Gtk.Box
     _onFullscreenButtonClicked(button)
     {
     }
-
-    _onIconThemeChanged(iconTheme)
-    {
-        /* Those icons are new, so check if theme has them */
-        this.hasPipIcons = (
-            iconTheme.has_icon('pip-in-symbolic')
-            && iconTheme.has_icon('pip-out-symbolic')
-        );
-    }
 });
 
 var HeaderBarPopover = GObject.registerClass({