[Chromium] Unreviewed gardening of two svg/zoom/page tests.

This change rebaselines two tests for WK108108.

Unreviewed update of test expectations.

* platform/chromium-mac/svg/zoom/page/zoom-background-images-expected.png:
* platform/chromium-mac/svg/zoom/page/zoom-svg-as-background-with-relative-size-expected.png:
* platform/chromium/TestExpectations:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@141644 268f45cc-cd09-0410-ab3c-d52691b4dbfc