Map/Set: Implement constructor parameter handling
When an iterable object is passed in as the argument to the Map and Set
constructor the elements of the iterable object are used to populate the
Map and Set.
http://people.mozilla.org/~jorendorff/es6-draft.html#sec-map-iterable
http://people.mozilla.org/~jorendorff/es6-draft.html#sec-set-iterable
BUG=v8:3398
LOG=Y
R=rossberg@chromium.org
Review URL: https://codereview.chromium.org/
345613003
Patch from Erik Arvidsson <arv@chromium.org>.
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21950
ce2b1a6d-e550-0410-aec6-
3dcde31c8c00