Add testharness.js based tests for ensuring correct ligature linebreaking

Permission for using MEgalopolis Font from Jack Usine was retrieved.

BUG=331514
R=dpranke,eae

Review URL: https://codereview.chromium.org/136523003

git-svn-id: svn://svn.chromium.org/blink/trunk@165215 bbb929c8-8fbe-4397-9dbb-9b2b20218538