add Promise

Promise are added from rev22.
http://wiki.ecmascript.org/doku.php?id=harmony:specification_drafts#january_20_2014_draft_rev_22
update the section number of Proxy
add Realm

Realm are added from rev22.
http://wiki.ecmascript.org/doku.php?id=harmony:specification_drafts#january_20_2014_draft_rev_22
add Loader

Loader are added from rev22.
http://wiki.ecmascript.org/doku.php?id=harmony:specification_drafts#january_20_2014_draft_rev_22
fix typos
add Function.prototype.toMethod

Function.prototype.toMethod are added from rev22.
http://wiki.ecmascript.org/doku.php?id=harmony:specification_drafts#january_20_2014_draft_rev_22
replace Number.prototype.clz with Math.clz32

Math.clz32 are added from rev23.
http://wiki.ecmascript.org/doku.php?id=harmony:specification_drafts#april_5_2014_draft_rev_23
remove "-0" setting from Map and Set

Now, Map and Set use the SameValueZero comparision algorithm, not SameValue.
https://people.mozilla.org/~jorendorff/es6-draft.html#sec-map-objects
https://people.mozilla.org/~jorendorff/es6-draft.html#sec-set-objects
https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero
stop using "new" operator in Symbols

"The Symbol constructor is not intended to be used with the new operator or to be subclassed."
https://people.mozilla.org/~jorendorff/es6-draft.html#sec-symbol-constructor
correct a mistake about hasOwn function's parameter in Symbols
update Symbols
update Reflect
add System
update revision
Merge pull request #5 from syoichi/pr3-update

Add Promise, Realm, Loader, System & Update Symbol, Reflect