Remove Objective-C reserved words from IDL test cases

Decrufting: we no longer have Objective-C bindings, and Code Generator
has no special casing for these reserved words, so the test cases are
no longer needed.

NOTRY=true

Review URL: https://codereview.chromium.org/51973004

git-svn-id: svn://svn.chromium.org/blink/trunk@160900 bbb929c8-8fbe-4397-9dbb-9b2b20218538