Revert "Fix toolbar button size on Qt 6.2"

Breaks running with Qt 5.9

This reverts commit 84ea483b4c.

app/gui/NavigableToolButton.qml

@@ -1,16 +1,9 @@
 import QtQuick 2.0
 import QtQuick.Controls 2.2
 
-// We use a RoundButton instead of a ToolButton because ToolButton
+ToolButton {
-// doesn't seem to like to be sized larger than normal on Qt 6.2.
-RoundButton {
     property string iconSource
 
-    // Style like a ToolButton
-    leftInset: 0
-    rightInset: 0
-    flat: true
-
     activeFocusOnTab: true
 
     // FIXME: We're using an Image here rather than icon.source because
@@ -20,15 +13,15 @@ RoundButton {
         source: iconSource
         anchors.centerIn: parent.background
         sourceSize {
-            width: parent.background.width * 0.80
+            width: parent.background.width * 1.10
-            height: parent.background.height * 0.80
+            height: parent.background.height * 1.10
         }
     }
 
     // This determines the size of the Material highlight. We increase it
     // from the default because we use larger than normal icons for TV readability.
-    background.implicitWidth: (parent.height - parent.anchors.bottomMargin - parent.anchors.topMargin) * 0.80
+    background.width: (parent.height - parent.anchors.bottomMargin - parent.anchors.topMargin) * 0.60
-    background.implicitHeight: (parent.height - parent.anchors.bottomMargin - parent.anchors.topMargin) * 0.80
+    background.height: (parent.height - parent.anchors.bottomMargin - parent.anchors.topMargin) * 0.60
 
     Keys.onReturnPressed: {
         clicked()