Rename privateTemplateXXX() to domTemplateXXX()

This is a preparation CL for removing worldType() from domTemplate(). This rename will make the CL diff saner.

NOTRY=true
BUG=339800

Review URL: https://codereview.chromium.org/145843004

git-svn-id: svn://svn.chromium.org/blink/trunk@167411 bbb929c8-8fbe-4397-9dbb-9b2b20218538