IDL compiler: [CheckSecurity=Frame] interfaces (initial)

This adds support for [CheckSecurity=Frame] interface,
but not for [CheckSecurity] + [DoNotCheckSecurity], as in:
[CheckSecurity=Frame] interface { [DoNotCheckSecurity] void foo(); };
(i.e., DomainSafeFunctionGetter/Setter).

BUG=239771

Review URL: https://codereview.chromium.org/61523003

git-svn-id: svn://svn.chromium.org/blink/trunk@162286 bbb929c8-8fbe-4397-9dbb-9b2b20218538