Rename and consolidate tests in reserved-words directory

test/language/reserved-words/7.6.1-4-6.js

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

test/language/reserved-words/7.6.1-4-8.js

test/language/reserved-words/7.6.1-4-9.js

test/language/reserved-words/7.6.1-5-1.js

test/language/reserved-words/7.6.1-5-10.js

test/language/reserved-words/7.6.1-5-11.js

test/language/reserved-words/7.6.1-5-13.js

test/language/reserved-words/7.6.1-5-14.js

test/language/reserved-words/7.6.1-5-15.js

test/language/reserved-words/7.6.1-5-16.js

test/language/reserved-words/7.6.1-5-2.js

test/language/reserved-words/7.6.1-5-3.js

test/language/reserved-words/7.6.1-5-4.js

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

test/language/reserved-words/7.6.1-5-6.js

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

test/language/reserved-words/7.6.1-5-8.js

test/language/reserved-words/7.6.1-5-9.js

test/language/reserved-words/7.6.1-6-1.js