Rename and consolidate tests in reserved-words directory

test/language/reserved-words/7.6.1-7-15.js

test/language/reserved-words/7.6.1-7-16.js

test/language/reserved-words/7.6.1-7-2.js

test/language/reserved-words/7.6.1-7-3.js

test/language/reserved-words/7.6.1-7-4.js

test/language/reserved-words/7.6.1-7-5.js

test/language/reserved-words/7.6.1-7-6.js

test/language/reserved-words/7.6.1-7-7.js

test/language/reserved-words/7.6.1-7-8.js

test/language/reserved-words/7.6.1-7-9.js

test/language/reserved-words/7.6.1-8-1.js

test/language/reserved-words/7.6.1-8-10.js

test/language/reserved-words/7.6.1-8-11.js

test/language/reserved-words/7.6.1-8-12.js

test/language/reserved-words/7.6.1-8-13.js

test/language/reserved-words/7.6.1-8-14.js

test/language/reserved-words/7.6.1-8-15.js

test/language/reserved-words/7.6.1-8-16.js

test/language/reserved-words/7.6.1-8-2.js

test/language/reserved-words/7.6.1-8-3.js