LibWeb: Return a dummy value from various SVG getters

Instead of crashing with a TODO() on half of the test cases generated by
Domato, let's just return a zeroed-out SVGAnimatedLength or
SVGAnimatedNumber from getters that return them.

We'll eventually have to implement these correctly, but crashing is not
productive since it blocks us from finding other issues.

Userland/Libraries/LibWeb/SVG/SVGLinearGradientElement.cpp

@@ -163,22 +163,26 @@ Optional<Gfx::PaintStyle const&> SVGLinearGradientElement::to_gfx_paint_style(SV
 
 JS::NonnullGCPtr<SVGAnimatedLength> SVGLinearGradientElement::x1() const
 {
-    TODO();
+    // FIXME: Implement this properly.
+    return SVGAnimatedLength::create(realm(), SVGLength::create(realm(), 0, 0), SVGLength::create(realm(), 0, 0));
 }
 
 JS::NonnullGCPtr<SVGAnimatedLength> SVGLinearGradientElement::y1() const
 {
-    TODO();
+    // FIXME: Implement this properly.
+    return SVGAnimatedLength::create(realm(), SVGLength::create(realm(), 0, 0), SVGLength::create(realm(), 0, 0));
 }
 
 JS::NonnullGCPtr<SVGAnimatedLength> SVGLinearGradientElement::x2() const
 {
-    TODO();
+    // FIXME: Implement this properly.
+    return SVGAnimatedLength::create(realm(), SVGLength::create(realm(), 0, 0), SVGLength::create(realm(), 0, 0));
 }
 
 JS::NonnullGCPtr<SVGAnimatedLength> SVGLinearGradientElement::y2() const
 {
-    TODO();
+    // FIXME: Implement this properly.
+    return SVGAnimatedLength::create(realm(), SVGLength::create(realm(), 0, 0), SVGLength::create(realm(), 0, 0));
 }
 
 }

Userland/Libraries/LibWeb/SVG/SVGRadialGradientElement.cpp

@@ -216,32 +216,38 @@ Optional<Gfx::PaintStyle const&> SVGRadialGradientElement::to_gfx_paint_style(SV
 
 JS::NonnullGCPtr<SVGAnimatedLength> SVGRadialGradientElement::cx() const
 {
-    TODO();
+    // FIXME: Implement this properly.
+    return SVGAnimatedLength::create(realm(), SVGLength::create(realm(), 0, 0), SVGLength::create(realm(), 0, 0));
 }
 
 JS::NonnullGCPtr<SVGAnimatedLength> SVGRadialGradientElement::cy() const
 {
-    TODO();
+    // FIXME: Implement this properly.
+    return SVGAnimatedLength::create(realm(), SVGLength::create(realm(), 0, 0), SVGLength::create(realm(), 0, 0));
 }
 
 JS::NonnullGCPtr<SVGAnimatedLength> SVGRadialGradientElement::fx() const
 {
-    TODO();
+    // FIXME: Implement this properly.
+    return SVGAnimatedLength::create(realm(), SVGLength::create(realm(), 0, 0), SVGLength::create(realm(), 0, 0));
 }
 
 JS::NonnullGCPtr<SVGAnimatedLength> SVGRadialGradientElement::fy() const
 {
-    TODO();
+    // FIXME: Implement this properly.
+    return SVGAnimatedLength::create(realm(), SVGLength::create(realm(), 0, 0), SVGLength::create(realm(), 0, 0));
 }
 
 JS::NonnullGCPtr<SVGAnimatedLength> SVGRadialGradientElement::fr() const
 {
-    TODO();
+    // FIXME: Implement this properly.
+    return SVGAnimatedLength::create(realm(), SVGLength::create(realm(), 0, 0), SVGLength::create(realm(), 0, 0));
 }
 
 JS::NonnullGCPtr<SVGAnimatedLength> SVGRadialGradientElement::r() const
 {
-    TODO();
+    // FIXME: Implement this properly.
+    return SVGAnimatedLength::create(realm(), SVGLength::create(realm(), 0, 0), SVGLength::create(realm(), 0, 0));
 }
 
 }

Userland/Libraries/LibWeb/SVG/SVGStopElement.cpp

@@ -62,7 +62,8 @@ float SVGStopElement::stop_opacity() const
 
 JS::NonnullGCPtr<SVGAnimatedNumber> SVGStopElement::offset() const
 {
-    TODO();
+    // FIXME: Implement this properly.
+    return SVGAnimatedNumber::create(realm(), 0, 0);
 }
 
 void SVGStopElement::initialize(JS::Realm& realm)

Userland/Libraries/LibWeb/SVG/SVGUseElement.cpp

@@ -163,12 +163,14 @@ JS::NonnullGCPtr<SVGAnimatedLength> SVGUseElement::y() const
 
 JS::NonnullGCPtr<SVGAnimatedLength> SVGUseElement::width() const
 {
-    TODO();
+    // FIXME: Implement this properly.
+    return SVGAnimatedLength::create(realm(), SVGLength::create(realm(), 0, 0), SVGLength::create(realm(), 0, 0));
 }
 
 JS::NonnullGCPtr<SVGAnimatedLength> SVGUseElement::height() const
 {
-    TODO();
+    // FIXME: Implement this properly.
+    return SVGAnimatedLength::create(realm(), SVGLength::create(realm(), 0, 0), SVGLength::create(realm(), 0, 0));
 }
 
 // https://svgwg.org/svg2-draft/struct.html#TermInstanceRoot