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

Author: https://github.com/AtkinsSJ
Commit: 116a1f485c
Pull-request: https://github.com/SerenityOS/serenity/pull/12444
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibWeb/SVG/AttributeNames.h

@@ -45,6 +45,7 @@ namespace Web::SVG::AttributeNames {
     E(patternContentUnits)          \
     E(patternTransform)             \
     E(patternUnits)                 \
+    E(points)                       \
     E(pointsAtX)                    \
     E(pointsAtY)                    \
     E(pointsAtZ)                    \