[4] Fix canvas rect bound calculation

It turns out the calculation of the bounding rect for canvas items has a nasty bug. When a transform is applied (especially in a custom draw), in the renderer this extra matrix is applied to all later commands in the canvas item. However in the calculation of the bound, the transform is only applied to the first command following the transform.

This PR fixes this inconsistency.

servers/rendering/renderer_canvas_render.h

@@ -420,7 +420,6 @@ public:
 
 				if (found_xform) {
 					r = xf.xform(r);
-					found_xform = false;
 				}
 
 				if (first) {