LibWeb: Limit the maximum size of <canvas> bitmap buffers

We will no longer create bitmap buffers for canvases that exceed a
total area of (16384 * 16384) pixels. This matches what some other
browser do.

Thanks to @itamar8910 for finding this! :^)

Libraries/LibWeb/Layout/LayoutCanvas.cpp

@@ -42,8 +42,8 @@ LayoutCanvas::~LayoutCanvas()
 
 void LayoutCanvas::layout()
 {
-    rect().set_width(node().preferred_width());
-    rect().set_height(node().preferred_height());
+    rect().set_width(node().requested_width());
+    rect().set_height(node().requested_height());
     LayoutReplaced::layout();
 }