comment and assertion
s/Tuple/Pair/ because the word "tuple" does not imply "two"
make TypedMap in src/util.jsx to be ES6 compatible

see http://people.mozilla.org/~jorendorff/es6-draft.html#sec-15.14.4.1
chnage TestCase specs

* show stack trace on failure
* test failure will stop executing the current test
add changes