Add impl IntoIterator on &Classes

[cecton]

Description

Since Classes is now cheap to clone, it only makes sense to be able to pass a
reference to a Classes to an extend method and having it clone all the things
automatically.

This is on par with &AttrValue being accepted in components properties.

Real life example:

use yew::prelude::*;
use yew::virtual_dom::AttrValue;

#[derive(Clone, PartialEq, Properties)]
pub struct ButtonGroupProps {
    #[prop_or_default]
    pub minimal: bool,
    #[prop_or_default]
    pub vertical: bool,
    #[prop_or_default]
    pub fill: bool,
    #[prop_or_default]
    pub large: bool,
    #[prop_or_default]
    pub style: Option<AttrValue>,
    #[prop_or_default]
    pub children: html::Children,
    #[prop_or_default]
    pub class: Classes,
}

#[function_component(ButtonGroup)]
pub fn button_group(props: &ButtonGroupProps) -> Html {
    let ButtonGroupProps {
        minimal,
        vertical,
        fill,
        large,
        style,
        children,
        class,
    } = props;

    html! {
        <div
            class={classes!(
                "bp3-button-group",
                minimal.then_some("bp3-minimal"),
                fill.then_some("bp3-fill"),
                large.then_some("bp3-large"),
                vertical.then_some("bp3-vertical"),
                class,              // <--- this PR change
            )}
            {style}                 // <-- already supported for AttrValue
        >
            {children.clone()}
        </div>
    }
}

Checklist

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

[github-actions]

Visit the preview URL for this PR (updated for commit 81acbcf):

https://yew-rs-api--pr3038-add-impl-from-ref-cl-hmjssapu.web.app

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[github-actions]

Benchmark - SSR

Yew Master

Details

Benchmark	Round	Min (ms)	Max (ms)	Mean (ms)	Standard Deviation
Baseline	10	344.252	345.825	344.792	0.499
Hello World	10	654.050	659.326	655.463	2.013
Function Router	10	2261.310	2274.487	2267.688	3.809
Concurrent Task	10	1008.314	1009.682	1009.000	0.463

Pull Request

Details

Benchmark	Round	Min (ms)	Max (ms)	Mean (ms)	Standard Deviation
Baseline	10	344.243	344.933	344.562	0.238
Hello World	10	646.877	651.143	648.079	1.560
Function Router	10	2284.957	2296.601	2290.855	3.548
Concurrent Task	10	1008.222	1009.675	1008.965	0.457

[github-actions]

Size Comparison

Details

examples	master (KB)	pull request (KB)	diff (KB)	diff (%)
async_clock	108.258	108.259	+0.001	+0.001%
boids	172.289	172.295	+0.006	+0.003%
communication_child_to_parent	92.363	92.360	-0.003	-0.003%
communication_grandchild_with_grandparent	106.797	106.799	+0.002	+0.002%
communication_grandparent_to_grandchild	102.658	102.652	-0.006	-0.006%
communication_parent_to_child	89.445	89.444	-0.001	-0.001%
contexts	109.335	109.336	+0.001	+0.001%
counter	87.386	87.385	-0.001	-0.001%
counter_functional	87.802	87.798	-0.004	-0.004%
dyn_create_destroy_apps	90.233	90.234	+0.001	+0.001%
file_upload	101.708	101.706	-0.002	-0.002%
function_memory_game	166.475	166.475	0	0.000%
function_router	350.031	350.035	+0.004	+0.001%
function_todomvc	161.419	161.418	-0.001	-0.001%
futures	226.534	226.535	+0.001	+0.000%
game_of_life	108.142	108.142	0	0.000%
immutable	183.999	183.999	0	0.000%
inner_html	83.808	83.807	-0.001	-0.001%
js_callback	113.015	113.009	-0.006	-0.005%
keyed_list	197.806	197.808	+0.002	+0.001%
mount_point	86.957	86.956	-0.001	-0.001%
nested_list	114.942	114.942	0	0.000%
node_refs	94.876	94.872	-0.004	-0.004%
password_strength	1552.856	1552.857	+0.001	+0.000%
portals	98.146	98.146	0	0.000%
router	320.127	320.122	-0.005	-0.002%
simple_ssr	153.047	153.056	+0.009	+0.006%
ssr_router	394.512	394.511	-0.001	-0.000%
suspense	110.762	110.762	0	0.000%
timer	90.282	90.279	-0.003	-0.003%
todomvc	142.749	142.748	-0.001	-0.001%
two_apps	88.016	88.014	-0.002	-0.002%
web_worker_fib	154.376	154.375	-0.001	-0.001%
webgl	86.532	86.533	+0.001	+0.001%

✅ None of the examples has changed their size significantly.

[WorldSEnder]

Makes sense to me to support this. Lgtm

[ranile]

Agreed, this is a nice addition!