classes transpiler: fix computed property + super

computed property must be calculated only once
objectliteral transpiler: __proto__ support
tests update
ability to pass filename with src
* es6 run-tests
generatorComprehension transpiler: small refactoring

generatorComprehension:
* use core.createVars
* function next(){} -> function next$0(){} to allow using 'next'
variable in comprehension
* Generator constructor is saved into Function["__Generator__"] to use
only one copy of constructor in different files

core.js:
* createVars: add 'self' parameter

* update tests
using core.createVars for more variables
add core.is and update all transpilers to using it
add 'transpiler/core/is' to build script