Preserve camelCase for known svg elements

[Madoshakalaka]

Description

This PR fixes SVG filter elements that require camelCase names (like feDropShadow) from being incorrectly lowercased, which causes them to not function at all in browsers.

The Problem

SVG filter effects completely stop working when their element names are lowercased:

<!-- This works in plain HTML -->
<feDropShadow dx="0" dy="0" stdDeviation="10" flood-color="red"/>

<!-- This is what Yew currently generates - DOES NOT WORK -->
<fedropshadow dx="0" dy="0" stddeviation="10" flood-color="red"/>

The browser does not recognize <fedropshadow> as a valid SVG filter primitive, so the entire filter effect is ignored.

The Fix

This PR modifies the tag name handling to:

• Preserve the original casing for known SVG elements (using the existing is_normalised_element_name function)
• Continue normalizing regular HTML elements to lowercase

This ensures SVG elements work correctly while maintaining the expected behavior for HTML elements.

Testing

Tested with a minimal reproduction:

• Before: SVG filters using feDropShadow, feGaussianBlur, etc. do not render
• After: SVG filters work correctly with preserved casing

Example

html! {
    <svg>
        <defs>
            <filter id="glow">
                <feDropShadow dx="0" dy="0" stdDeviation="10" flood-color="red"/>
            </filter>
        </defs>
        <rect width="100" height="100" filter="url(#glow)" />
    </svg>
}

[github-actions]

Visit the preview URL for this PR (updated for commit ce06bb1):

https://yew-rs-api--pr3875-fix-svg-filter-casin-4g31o9zo.web.app

_{(expires Wed, 23 Jul 2025 04:13:33 GMT)}

_{🔥 via Firebase Hosting GitHub Action 🌎}

[github-actions]

Benchmark - SSR

Yew Master

Benchmark	Round	Min (ms)	Max (ms)	Mean (ms)	Standard Deviation
Baseline	10	310.545	312.538	310.902	0.583
Hello World	10	463.620	515.075	475.294	16.397
Function Router	10	1595.565	1613.881	1601.096	5.824
Concurrent Task	10	1006.353	1008.001	1007.142	0.468
Many Providers	10	1060.612	1099.089	1072.984	12.671

Pull Request

Benchmark	Round	Min (ms)	Max (ms)	Mean (ms)	Standard Deviation
Baseline	10	310.511	311.213	310.776	0.197
Hello World	10	463.942	477.993	466.458	4.170
Function Router	10	1623.653	1640.453	1631.533	5.342
Concurrent Task	10	1005.780	1008.112	1007.167	0.613
Many Providers	10	1083.733	1117.613	1095.274	10.370

[github-actions]

Size Comparison

examples	master (KB)	pull request (KB)	diff (KB)	diff (%)
async_clock	99.752	99.752	0	0.000%
boids	168.697	168.697	0	0.000%
communication_child_to_parent	92.070	92.070	0	0.000%
communication_grandchild_with_grandparent	103.230	103.230	0	0.000%
communication_grandparent_to_grandchild	98.220	98.220	0	0.000%
communication_parent_to_child	87.927	87.927	0	0.000%
contexts	104.177	104.177	0	0.000%
counter	84.728	84.728	0	0.000%
counter_functional	85.077	85.077	0	0.000%
dyn_create_destroy_apps	87.655	87.655	0	0.000%
file_upload	98.911	98.911	0	0.000%
function_memory_game	170.503	170.503	0	0.000%
function_router	338.021	338.021	0	0.000%
function_todomvc	163.429	163.429	0	0.000%
futures	236.408	236.408	0	0.000%
game_of_life	104.759	104.759	0	0.000%
immutable	194.198	194.198	0	0.000%
inner_html	80.296	80.296	0	0.000%
js_callback	107.813	107.813	0	0.000%
keyed_list	196.043	196.043	0	0.000%
mount_point	83.604	83.604	0	0.000%
nested_list	112.981	112.981	0	0.000%
node_refs	90.975	90.975	0	0.000%
password_strength	1785.458	1785.458	0	0.000%
portals	92.921	92.921	0	0.000%
router	306.862	306.862	0	0.000%
suspense	111.862	111.862	0	0.000%
timer	88.809	88.809	0	0.000%
timer_functional	94.938	94.938	0	0.000%
todomvc	143.515	143.515	0	0.000%
two_apps	86.017	86.017	0	0.000%
web_worker_fib	135.158	135.158	0	0.000%
web_worker_prime	185.657	185.657	0	0.000%
webgl	83.244	83.244	0	0.000%

✅ None of the examples has changed their size significantly.

[Madoshakalaka]

@WorldSEnder what's your stance on this? I see you worked on #2578 which is related to this issue

[Madoshakalaka]

Related: #3871

Current yew actually panics during hydration while handling these dynamic camelCase svg elements,

It's currently impossible to use these svg elements in a SSR app: lowercase doesn't work, camelCase panics at hydration.

[its-the-shrimp]

Why does Yew even meddle with the element names? shouldn't it pass them to the browser as they're specified?