Remove the remaining ScriptState::current etc

This is the final bit of the work to remove "current" methods from the code base. I manually grepped all "current" methods from the code base and addressed the remaining ones in this CL.

BUG=357144

Review URL: https://codereview.chromium.org/310423002

git-svn-id: svn://svn.chromium.org/blink/trunk@175638 bbb929c8-8fbe-4397-9dbb-9b2b20218538