Replace big code block to build CSS pseudo name table with a loop.

Save 8 KB binary size by replacing code that expanded badly with
a loop. As a bonus, the code is much more maintainable now.

BUG=352113

R=ojan@chromium.org

Review URL: https://codereview.chromium.org/196983005

git-svn-id: svn://svn.chromium.org/blink/trunk@169175 bbb929c8-8fbe-4397-9dbb-9b2b20218538