LibWeb: Add an initial implementation of SVG text-anchor

This only handles very simple <text> elements, but this is enough (with
the font-size changes) to improve the badges on the GitHub README a fair
bit.

Userland/Libraries/LibWeb/SVG/SVGTextContentElement.h

@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <LibWeb/SVG/AttributeParser.h>
 #include <LibWeb/SVG/SVGGraphicsElement.h>
 #include <LibWeb/WebIDL/ExceptionOr.h>
 
@@ -24,6 +25,8 @@ public:
 
     Gfx::FloatPoint get_offset() const;
 
+    Optional<TextAnchor> text_anchor() const;
+
 protected:
     SVGTextContentElement(DOM::Document&, DOM::QualifiedName);