UpdateExpressions: add necessary changes to tests to reflect latest specification.

...guage/expressions/postfix-decrement/arguments-nostrict.js

test/language/expressions/postfix-decrement/arguments.js

test/language/expressions/postfix-decrement/eval-nostrict.js

test/language/expressions/postfix-decrement/eval.js

test/language/expressions/postfix-decrement/non-simple.js

...guage/expressions/postfix-increment/arguments-nostrict.js

test/language/expressions/postfix-increment/arguments.js

test/language/expressions/postfix-increment/eval-nostrict.js

test/language/expressions/postfix-increment/eval.js

test/language/expressions/postfix-increment/non-simple.js

...nguage/expressions/prefix-decrement/arguments-nostrict.js

test/language/expressions/prefix-decrement/arguments.js

test/language/expressions/prefix-decrement/eval-nostrict.js

test/language/expressions/prefix-decrement/eval.js

test/language/expressions/prefix-decrement/non-simple.js

...nguage/expressions/prefix-increment/arguments-nostrict.js

test/language/expressions/prefix-increment/arguments.js

test/language/expressions/prefix-increment/eval-nostrict.js

test/language/expressions/prefix-increment/eval.js

test/language/expressions/prefix-increment/non-simple.js