class fields: add ASI tests

test/language/expressions/class/fields-asi-1.js

test/language/expressions/class/fields-asi-2.js

test/language/expressions/class/fields-asi-3.js

test/language/expressions/class/fields-asi-4.js

test/language/expressions/class/fields-asi-5.js

test/language/statements/class/fields-asi-1.js

test/language/statements/class/fields-asi-2.js

test/language/statements/class/fields-asi-3.js

test/language/statements/class/fields-asi-4.js

test/language/statements/class/fields-asi-5.js