Encypted Media: Simplify isTypeSupported() layout test with "apply()".

The apply() method calls a function with a given this value and arguments provided as an array. Which is exactly what we need here.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply

BUG=224791

Review URL: https://codereview.chromium.org/177193003

git-svn-id: svn://svn.chromium.org/blink/trunk@168096 bbb929c8-8fbe-4397-9dbb-9b2b20218538