fix lazy-load of js_callback example

[hikaricai]

Description

js_callback example's lazy-load is not working because of rustwasm/wasm-bindgen#3208
try to fix this

Checklist

• I have reviewed my own code
• I have added tests

[github-actions]

Size Comparison

examples	master (KB)	pull request (KB)	diff (KB)	diff (%)
async_clock	104.041	104.041	0	0.000%
boids	174.640	174.640	0	0.000%
communication_child_to_parent	96.665	96.665	0	0.000%
communication_grandchild_with_grandparent	108.863	108.863	0	0.000%
communication_grandparent_to_grandchild	105.041	105.041	0	0.000%
communication_parent_to_child	93.715	93.715	0	0.000%
contexts	109.592	109.592	0	0.000%
counter	90.301	90.301	0	0.000%
counter_functional	90.695	90.695	0	0.000%
dyn_create_destroy_apps	93.053	93.053	0	0.000%
file_upload	104.390	104.390	0	0.000%
function_memory_game	169.278	169.278	0	0.000%
function_router	339.210	339.210	0	0.000%
function_todomvc	163.590	163.590	0	0.000%
futures	227.805	227.805	0	0.000%
game_of_life	110.480	110.480	0	0.000%
immutable	188.594	188.594	0	0.000%
inner_html	86.848	86.848	0	0.000%
js_callback	113.512	113.513	+0.001	+0.001%
keyed_list	201.919	201.919	0	0.000%
mount_point	89.972	89.972	0	0.000%
nested_list	114.476	114.476	0	0.000%
node_refs	97.456	97.456	0	0.000%
password_strength	1588.925	1588.925	0	0.000%
portals	98.753	98.753	0	0.000%
router	310.062	310.062	0	0.000%
simple_ssr	145.152	145.152	0	0.000%
ssr_router	377.358	377.358	0	0.000%
suspense	111.200	111.200	0	0.000%
timer	93.073	93.073	0	0.000%
timer_functional	101.387	101.387	0	0.000%
todomvc	144.858	144.858	0	0.000%
two_apps	90.895	90.895	0	0.000%
web_worker_fib	155.312	155.312	0	0.000%
webgl	89.402	89.402	0	0.000%

✅ None of the examples has changed their size significantly.

[futursolo]

Thank you for the fix.

[ranile]

Thanks!