IDL compiler: typed array types for setters

Simple one, just add 2 branches to v8_types.py.

(Current patch has redundant *_type => is_*_type renaming,
will disappear when enum CL lands and I rebase.)

BUG=239771
NOTRY=true

Review URL: https://codereview.chromium.org/30433002

git-svn-id: svn://svn.chromium.org/blink/trunk@160009 bbb929c8-8fbe-4397-9dbb-9b2b20218538