DevTools: get rid of Element.prototype.removeMatchingStyleClasses

This method encourages className crafting and runs unexpectedly long.

BUG=316092
NOTRY=true

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=180163

Review URL: https://codereview.chromium.org/466703002

git-svn-id: svn://svn.chromium.org/blink/trunk@180172 bbb929c8-8fbe-4397-9dbb-9b2b20218538