LibWeb: Add initial support for SVG <textPath>

This patch adds basic support for the SVG `<textPath>`, so it supports
placing text along a path, but none of the extra attributes for
controlling the layout of the text. This is enough to correctly display
the MDN example.

Userland/Libraries/LibWeb/CMakeLists.txt

@@ -458,6 +458,7 @@ set(SOURCES
     Layout/SVGGraphicsBox.cpp
     Layout/SVGSVGBox.cpp
     Layout/SVGTextBox.cpp
+    Layout/SVGTextPathBox.cpp
     Layout/TableFormattingContext.cpp
     Layout/TableGrid.cpp
     Layout/TableWrapper.cpp
@@ -584,6 +585,7 @@ set(SOURCES
     SVG/SVGSymbolElement.cpp
     SVG/SVGTextContentElement.cpp
     SVG/SVGTextElement.cpp
+    SVG/SVGTextPathElement.cpp
     SVG/SVGTextPositioningElement.cpp
     SVG/SVGTitleElement.cpp
     SVG/SVGTSpanElement.cpp