LibWeb: Add SVG <line> element and test case :^)

Author: https://github.com/AtkinsSJ
Commit: 17912330c4
Pull-request: https://github.com/SerenityOS/serenity/pull/12444
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibWeb/Forward.h

@@ -249,6 +249,7 @@ class SVGElement;
 class SVGEllipseElement;
 class SVGGeometryElement;
 class SVGGraphicsElement;
+class SVGLineElement;
 class SVGPathElement;
 class SVGRectElement;
 class SVGSVGElement;
@@ -457,6 +458,7 @@ class SVGElementWrapper;
 class SVGEllipseElementWrapper;
 class SVGGeometryElementWrapper;
 class SVGGraphicsElementWrapper;
+class SVGLineElementWrapper;
 class SVGPathElementWrapper;
 class SVGRectElementWrapper;
 class SVGSVGElementWrapper;