LibWeb: Extract CanvasPath class from CRC2D

This better matches the spec, and makes it possible for things like
Path2D to reuse the same implementation without duplicate code. :^)

Userland/Libraries/LibWeb/HTML/Canvas/CanvasPath.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2022, Sam Atkins <atkinssj@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibGfx/Path.h>
+#include <LibWeb/DOM/ExceptionOr.h>
+
+namespace Web::HTML {
+
+// https://html.spec.whatwg.org/multipage/canvas.html#canvaspath
+class CanvasPath {
+public:
+    ~CanvasPath() = default;
+
+    void close_path();
+
+    void move_to(float x, float y);
+    void line_to(float x, float y);
+    void quadratic_curve_to(float cx, float cy, float x, float y);
+    void bezier_curve_to(double cp1x, double cp1y, double cp2x, double cp2y, double x, double y);
+    void rect(float x, float y, float width, float height);
+    DOM::ExceptionOr<void> arc(float x, float y, float radius, float start_angle, float end_angle, bool counter_clockwise);
+    DOM::ExceptionOr<void> ellipse(float x, float y, float radius_x, float radius_y, float rotation, float start_angle, float end_angle, bool counter_clockwise);
+
+    Gfx::Path& path() { return m_path; }
+    Gfx::Path const& path() const { return m_path; }
+
+protected:
+    CanvasPath() = default;
+
+private:
+    Gfx::Path m_path;
+};
+
+}