many ops don't call ToPrimitive

the [kangax test for Symbol.toPrimitive](http://kangax.github.io/compat-table/es6/) fails for ejs because a few of the ops don't call ToPrimitive.

Probably most importantly, we're missing an implementation of [Abstract Relational Comparison](http://people.mozilla.org/~jorendorff/es6-draft.html#sec-abstract-relational-comparison).
