[Bug]: Modal-wrapper block-size style is not being set in Safari or Firefox

### Code of conduct

- [x] I agree to follow this project's code of conduct.

### Impacted component(s)

sp-dialog-base

### Library version

1.9.0

### Expected behavior

`block-size` should be set on `sp-dialog-base`.

### Actual behavior

`block-size` is not set on `sp-dialog-base` on Firefox or Safari.

### Screenshots

### What browsers are you seeing the problem in?

Safari, Firefox

### How can we reproduce this issue?

1. Go to https://opensource.adobe.com/spectrum-web-components/storybook/index.html?path=/story/dialog-base--slotted&globals=system:spectrum-two
2. Inspect sp-dialog-base
3. Search for the `block-size` style

### Sample code or abstract reproduction which illustrates the problem

https://github.com/adobe/spectrum-web-components/blob/main/1st-gen/packages/modal/src/spectrum-modal-wrapper.css#L16-L18

### Severity

None

### Logs taken while reproducing problem

_No response_

### Would you like to track this issue in Jira?

- [x] Yes, please tell me the ticket number!

Open 1st-gen/packages/modal/src/spectrum-modal-wrapper.css at lines 16-18 and reproduce the issue using the linked Storybook sp-dialog-base slotted example. Inspect sp-dialog-base in Safari and Firefox; done means the block-size style is set there in both browsers.

Written by the indexing model from the issue text.