[web] Correctly read the repetitionCount for images

[harryterkelsen]

There was a bug in ResizingCodec where it returned frameCount instead of repetitionCount in the repetitionCount getter, causing animated images to stop animating even if they were set to loop infinitely.

Fixes #161800

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[yjbanov]

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Changes reported for pull request #162414 at sha 7c6c0af