Removed superseeded prefixed CSS properties histogram
Removed superseeded prefixed CSS properties histogram

r150654 added an histogram for all CSS properties so we don't need
to measure the subset of prefixed CSS properties anymore.
Also the CSS prefixed properties' histogram has several shortcomings:
- CSS properties IDs are not stable.
- you would need to do some math to figure out the actual IDs from
the results.

Review URL: https://chromiumcodereview.appspot.com/16821007

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@152331 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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