Avoid using non-standard property names in test

For bug 290055, two use counters was added for how CSSStyleDeclaration
is indexed. One is using non-standard literal names for the CSS
properties, i.e using elt.style['font-size'] instead of
elt.style['fontSize']. The other one is using 'float' instead of
'cssFloat'. Avoid measuring the use counter code in performance tests
by using the standard names instead.

BUG=313864

Review URL: https://codereview.chromium.org/98733002

git-svn-id: svn://svn.chromium.org/blink/trunk@162981 bbb929c8-8fbe-4397-9dbb-9b2b20218538