fix `cljs.test/testing so that it works as an stand alone expression. Change all the `cljs.test/is` macro helpers include the last value in the environment so that we can use it later.
fix `cljs.test/testing so that it works as an stand alone
expression. Change all the `cljs.test/is` macro helpers include the
last value in the environment so that we can use it later.

mstang/clojurescript,mstang/clojurescript,mstang/clojurescript