Ensuring tabs collapse in small screens on <iOS 13

[arapehl]

WHY are these changes introduced?

Fixes: #1677
Fixes: https://github.com/Shopify/online-store-web/issues/4667

WHAT is this pull request doing?

Causes <Tabs /> component to collapse correctly on small screens in pre-iOS 13 versions of Safari. The screenshots go back to iOS 11 but it fixes the issue all the way back to iOS 9. (The tabs don't render properly in iOS 8.)

Before	After

How to 🎩

🖥 Local development instructions
🗒 General tophatting guidelines
📄 Changelog guidelines

Copy-paste this code in playground/Playground.tsx:

import React from 'react';
import {Page} from '../src';

export function Playground() {
  return (
    <Page title="Playground">
      {/* Add the code you want to test in here */}
    </Page>
  );
}

🎩 checklist

• Tested on mobile
• Tested on multiple browsers
• Tested for accessibility
• Updated the component's README.md with documentation changes
• Tophatted documentation changes in the style guide
• For visual design changes, pinged one of @ HYPD, @ mirualves, @ sarahill, or @ ry5n to update the Polaris UI kit

[github-actions]

Results

💦 Potential splash zone of changes introduced to src/**/*.tsx in this pull request:

Files modified	2
Files potentially affected	1

Details

All files potentially affected (total: 1)

• /src/components/Tabs/Tabs.tsx

❔ UNRELEASED.md (total: 0)

Files potentially affected (total: 0)

🎨 src/components/Tabs/Tabs.scss (total: 1)

Files potentially affected (total: 1)

• /src/components/Tabs/Tabs.tsx

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This comment automatically updates as changes are made to this pull request.
Feedback, troubleshooting: open an issue or reach out on Slack in #polaris-tooling.

[beefchimi]

🎩 🚢

[dleroux]

Thanks for doing this!