[BUG] Cannot read property 'width' of null for Webkit screenshot

[mmarkelov]

Context:

• Playwright Version: [0.10.0]
• Operating System: [Mac]

Code Snippet

const playwright = require('playwright');

(async () => {
    for (const browserType of ['chromium', 'firefox', 'webkit']) {
        const browser = await playwright[browserType].launch();
        const context = await browser.newContext({viewport: null});
        const page = await context.newPage('https://whatismybrowser.com/');

        await page.screenshot({ path: `example-${browserType}.png` });
        await browser.close();
    }
})();

Describe the bug

According to documentation viewport option can be null. And in this case I got error with Webkit: UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'width' of null from here:

playwright/src/webkit/wkPage.ts

Line 493 in d397bb1

const rect = options.clip || { x: 0, y: 0, width: viewportSize.width, height: viewportSize.height };

So I suppose it should have some checks for viewport.

I can make PR to fix this.
Thanks!

[pavelfeldman]

Thanks for the report! I'll use this opportunity to rearrange some of the logic and add a test for this one, hesitant asking for a PR here due to all this extra work.