LibWeb: Move SVGPathElement methods into SVGGeometryElement

From the spec:

> Interface SVGGeometryElement represents SVG elements whose rendering
> is defined by geometry with an equivalent path, and which can be
> filled and stroked. This includes paths and the basic shapes.

- https://svgwg.org/svg2-draft/types.html#InterfaceSVGGeometryElement

Making them all create an SVGPathBox, and return a Path from get_path(),
means we can implement the "basic shapes" using the path system we
already have. :^)

Userland/Libraries/LibWeb/SVG/SVGGeometryElement.cpp

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <LibWeb/Layout/SVGPathBox.h>
 #include <LibWeb/SVG/SVGGeometryElement.h>
 
 namespace Web::SVG {
@@ -13,4 +14,9 @@ SVGGeometryElement::SVGGeometryElement(DOM::Document& document, QualifiedName qu
 {
 }
 
+RefPtr<Layout::Node> SVGGeometryElement::create_layout_node(NonnullRefPtr<CSS::StyleProperties> style)
+{
+    return adopt_ref(*new Layout::SVGPathBox(document(), *this, move(style)));
+}
+
 }