Revert 159954 "Improve tests, related to zooming ImageDocuments."

> Improve tests, related to zooming ImageDocuments.
> 
> Previously, these tests relied on resize events, which is not necessary,
> since zooms are synchronous. I compacted the two tests into one and
> made them a bit more value-resilient -- instead of just printing values,
> they actually tests for size equality.
> 
> BUG=307570
> R=eseidel@chromium.org, tony
> 
> Review URL: https://codereview.chromium.org/29543002

TBR=dglazkov@chromium.org

Review URL: https://codereview.chromium.org/29593002

git-svn-id: svn://svn.chromium.org/blink/trunk@159955 bbb929c8-8fbe-4397-9dbb-9b2b20218538