Replace runTestCase with assert helpers [test/language/expressions]

test/language/expressions/assignment/11.13.1-4-1.js

test/language/expressions/assignment/11.13.1-4-27-s.js

test/language/expressions/assignment/11.13.1-4-28-s.js

test/language/expressions/assignment/11.13.1-4-29-s.js

test/language/expressions/assignment/11.13.1-4-31-s.js

test/language/expressions/assignment/8.12.5-3-b_1.js

test/language/expressions/assignment/8.12.5-3-b_2.js

test/language/expressions/assignment/8.12.5-5-b_1.js

...anguage/expressions/compound-assignment/11.13.2-6-12-s.js

...anguage/expressions/compound-assignment/11.13.2-6-13-s.js

...anguage/expressions/compound-assignment/11.13.2-6-14-s.js

...anguage/expressions/compound-assignment/11.13.2-6-15-s.js

...anguage/expressions/compound-assignment/11.13.2-6-16-s.js

...anguage/expressions/compound-assignment/11.13.2-6-17-s.js

...anguage/expressions/compound-assignment/11.13.2-6-18-s.js

...anguage/expressions/compound-assignment/11.13.2-6-19-s.js

...anguage/expressions/compound-assignment/11.13.2-6-20-s.js

...anguage/expressions/compound-assignment/11.13.2-6-21-s.js

...anguage/expressions/compound-assignment/11.13.2-6-22-s.js

test/language/expressions/delete/11.4.1-0-1.js