fix: defaultViewport can be null in BrowserConnectOptions

[zoltan-boros]

Steps to reproduce

Description:

As per API defaultViewport field in launch options ( puppeteer.lauch( { defaultViewport: ... } ) link ) can have the three below values:

• Viewport object - The specified viewport will be applied.
• undefined (i.e. defaultViewport field is absent) - Default viewport will be applied.
• null - No viewport will be applied. Useful in headful mode, because page content will accomodate to browser extent.

Tell us about your environment:

• Puppeteer version: 8.0.0
• Platform / OS version: N/A
• URLs (if applicable):

  puppeteer/src/common/BrowserConnector.ts

  Line 40 in 0b5969d

  defaultViewport?: Viewport;

• Node.js version: N/A

What steps will reproduce the problem?

1. Create a TypeScript project that launches a Chromium instance using puppeteer.launch(options) function.
2. Among options specify defaultViewport field as null.

Please include code that reproduces the issue.

puppeteer.lauch({
  headless: false,
  defaultViewport: null,
});

What is the expected result?

Code is accepted as valid, no type error raises.

What happens instead?

Type error raises, which tells that null is not valid value for defaultViewport.

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[zoltan-boros]

@googlebot I signed it!

[sadym-chromium]

Could you please add more details? Ideally - open an issue justifying the need of the change.
What is the use-case when the defaultViewport is null?

[zoltan-boros]

@sadym-chromium, thank you for the advice.
I added details.

[L0tso]

@sadym-chromium Another open pull request with linked issues #6942
Also, according to spec defaultViewport <?Object> Sets a consistent viewport for each page. Defaults to an 800x600 viewport. null disables the default viewport. null disables the default viewport.

[zoltan-boros]

@sadym-chromium thank you for your review and approval.
I realized that #6942 is the proper fix of the same issue.
I would close this issue in favour of #6942. Could you review that one, please?

[zoltan-boros]

Closed in favour of #6942