Fixed displaying Cesium Ion icon in WebView

[vividos]

When running in a WebView on Android, iOS or UWP WebView, the base URL either starts with file:/// or ms-appx-web:///. When the Credits object for Cesium Ion is created, the <img> tag contains a src attribute with this base URL. The integrated DOMpurify strips all src tags which doesn't contain http or https URLs. This fix changes the src attribute to contain an absolute Url in that case.

This PR doesn't need my other try at fixing the Ion icon issue, PR #8669, as it would also work without it.

Fixes #8665.

[cesium-concierge]

Thanks for the pull request @vividos!

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• Cesium Viewer works.
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[vividos]

@OmarShehata Could you please take a look at this PR and test it with your Cordova test app? Also there is an error from the Prettier tool that I tried to fix, but unfortunately the tool doesn't exactly say what the issue is. Thanks!

[vividos]

@OmarShehata I finally got it working with Prettier not reporting any issues now.

[vividos]

@mramato @lilleyse Maybe you could take a look at this PR and consider it for the next version? I'll rebase it on the latest master. Thanks!

[OmarShehata]

@vividos thanks for continuing to investigate this. I can confirm this PR fixes the issue on Android with Cordova and makes the Cesium ion logo correctly appear.

@mramato this is the correct approach as far as I'm aware but would love to get a second opinion when you have a chance to take a look. This requires a change in ThirdParty code that we're using to parse URLs which is producing incorrect behavior as I mentioned here: #8669 (comment)

For what to do with this PR, @mramato the behavior for parsing URIs with file:/// (three slashes, no authority or hostname) is incorrect in master, and is fixed in this PR. Sandcastle with test case here #8665 (comment).

I'm not aware of a way to fix this without modifying the third party code, since ThirdParty/Uri.js incorrectly skips the // when the authority and hostname are blank. I would merge this after unit tests are added for it but wanted to get a second opinion here.

[vividos]

@OmarShehata A short comment from me, this PR only changes CreditDisplay.js, where the <img src is specified. Using an absolute path, without file:// prevents the DOMPurify to remove the src attribute altogether.

The other PR from me, #8669, is not necessary to fix the Ion icon, and that PR modifies the third-party code.

[OmarShehata]

Oh great! My bad for missing that @vividos . This change looks good to me then, and perhaps we can revisit the ThirdParty/Url.js fix when we have more time.

Congrats on your first merged contribution to CesiumJS Michael!