Userland+LibGUI: Add shorthand versions of the Margins constructor

This allows for typing [8] instead of [8, 8, 8, 8] to specify the same
margin on all edges, for example. The constructors follow CSS' style of
specifying margins. The added constructors are:

- Margins(int all): Sets the same margin on all edges.
- Margins(int vertical, int horizontal): Sets the first argument to top
  and bottom margins, and the second argument to left and right margins.
- Margins(int top, int vertical, int bottom): Sets the first argument to
  the top margin, the second argument to the left and right margins,
  and the third argument to the bottom margin.

1 files changed, 1 insertions, 1 deletions

diff --git a/Userland/Demos/WidgetGallery/DemoWizardPage1.gml b/Userland/Demos/WidgetGallery/DemoWizardPage1.gml
index 136ff9296c..047eb38fbf 100644
--- a/Userland/Demos/WidgetGallery/DemoWizardPage1.gml
+++ b/Userland/Demos/WidgetGallery/DemoWizardPage1.gml
@@ -1,6 +1,6 @@
 @GUI::Widget {
     layout: @GUI::VerticalBoxLayout {
-        margins: [20, 20, 20, 20]
+        margins: [20]
     }
 
     @GUI::Label {