DevTools: move layout test styles-new-API.html to the testSuite

The patch simplifies layout test structure via using test suite instead
of a callback chain.

BUG=

Review URL: https://codereview.chromium.org/163233004

git-svn-id: svn://svn.chromium.org/blink/trunk@167185 bbb929c8-8fbe-4397-9dbb-9b2b20218538