Fix LayoutTest opacity-transform-animation.html

The current expectation uses the wrong opacity value.

Also animate over a greater range of opacity values to make the test easier to eyeball.

R=dstockwell

Review URL: https://codereview.chromium.org/38943002

git-svn-id: svn://svn.chromium.org/blink/trunk@160418 bbb929c8-8fbe-4397-9dbb-9b2b20218538