Replace runTestCase with assert helpers [test/language/reserved-words]

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

test/language/reserved-words/7.6.1-1-10.js

test/language/reserved-words/7.6.1-1-11.js

test/language/reserved-words/7.6.1-1-12.js

test/language/reserved-words/7.6.1-1-13.js

test/language/reserved-words/7.6.1-1-14.js

test/language/reserved-words/7.6.1-1-15.js

test/language/reserved-words/7.6.1-1-16.js

test/language/reserved-words/7.6.1-1-2.js

test/language/reserved-words/7.6.1-1-3.js

test/language/reserved-words/7.6.1-1-4.js

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

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

test/language/reserved-words/7.6.1-1-7.js

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

test/language/reserved-words/7.6.1-1-9.js

test/language/reserved-words/7.6.1-2-1.js

test/language/reserved-words/7.6.1-2-10.js

test/language/reserved-words/7.6.1-2-11.js

test/language/reserved-words/7.6.1-2-12.js