IDL compiler: [ActiveDOMObject] interface

First interface extended attribute.

Each of these requires a separate test IDL file,
as do combinations of extended attributes that interact,
due to having one interface per file.

The test interface can be *empty* if the extended attribute 
only affects the overall interface code (e.g., [ActiveDOMObject]),
but needs to have attributes or methods if these are also affected
(e.g., [CheckSecurity]).

I will be primarily activating existing tests by removing the "SKIP" from
run-bindings-tests, and writing new tests if necessary.
Following existing naming, these are generally called
Test<ExtAttr>Interface.idl
...for some value of <ExtAttr>.

This CL also renames an incorrectly named file:
TestActiveDOMObject.idl => TestCheckSecurityInterface.idl
...and adds a new test file:
TestActiveDOMObjectInterface.idl

BUG=239771
NOTRY=true

Review URL: https://codereview.chromium.org/74783008

git-svn-id: svn://svn.chromium.org/blink/trunk@162256 bbb929c8-8fbe-4397-9dbb-9b2b20218538