Add feature flags for new.target

[IgnoredAmbience]

Add feature flags for new.target

Commit additionally removes the arrow-function feature for
test/language/eval-code/direct/new.target-fn.js as it is not testing
arrow-functions, but they are mentioned in the preamble.

[IgnoredAmbience]

I'm confused as to why the build has failed, CONTRIBUTING.md says:

Tests expressed with this convention are built automatically following the source files' acceptance into the project. Patches should not include assets built from these sources.

But the CI build has failed with:

$ ./tools/scripts/ci_build.sh
Running target: build
> /home/travis/virtualenv/python2.7.14/bin/python tools/generation/generator.py create --out test src
New changes were found after re-generating the tests.
Please, read the documentation on procedurally generated tests
https://github.com/tc39/test262/blob/master/CONTRIBUTING.md#procedurally-generated-tests
The command "./tools/scripts/ci_build.sh" exited with 1.

These two statements seem contradictory?

[rwaldron]

No problem, I pulled this and regenerated the generated tests. I've opened a PR at: #1649 (which has your original commit in it)