ES6: Add support for Map/Set forEach

ES6: Add support for Map/Set forEach

This implements MapIterator and SetIterator which matches
the same constructs in the ES6 spec. However, these 2
iterators are not exposed to user code yet. They are only
used internally to implement Map.prototype.forEach and
Set.prototype.forEach.

Each iterator has a reference to the OrderedHashTable where
it directly accesses the hash table's entries.

The OrderedHashTable has a reference to the newest iterator
and each iterator has a reference to the next and previous
iterator, effectively creating a double linked list.

When the OrderedHashTable is mutated (or replaced) all the
iterators are updated.

When the iterator iterates passed the end of the data table
it closes itself. Closed iterators no longer have a
reference to the OrderedHashTable and they are removed from
the double linked list. In the case of Map/Set forEach, we
manually call Close on the iterator in case an exception was
thrown so that the iterator never reached the end.

At this point the OrderedHashTable keeps all the non finished
iterators alive but since the only thing we currently expose
is forEach there are no unfinished iterators outside a forEach
call. Once we expose the iterators to user code we will need
to make the references from the OrderedHashTable to the
iterators weak and have some mechanism to close an iterator
when it is garbage collected.

BUG=1793, 2323
LOG=Y
R=adamk@chromium.org
TBR=mstarzinger@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=20857

[arv (Not doing code reviews), 2014-04-16 22:03:50]

Now with explicit instantiation of all the functions instead of explicit
instantiation of the class

[adamk, 2014-04-16 22:13:14]

https://codereview.chromium.org/238063009/diff/1/src/objects.cc
File src/objects.cc (right):

https://codereview.chromium.org/238063009/diff/1/src/objects.cc#newcode16532
src/objects.cc:16532: OrderedHashTable<OrderedHashSet, JSSetIterator,
1>::Rehash(
This is private, so all calls are almost certainly in this file. I don't think
you need this one (or the Map one, below).

https://codereview.chromium.org/238063009/diff/1/src/objects.cc#newcode16752
src/objects.cc:16752: #define EXPLICIT_INSTANTIATE_ACCESSOR(Derived, TableType,
name, type)     \
These all have definitions in objects-inl.h, right? Those should be available to
anyone who needs to instantiate them, so this section looks definitely
unnecessary to me.

https://codereview.chromium.org/238063009/diff/1/src/objects.cc#newcode16785
src/objects.cc:16785: OrderedHashTableIterator<JSSetIterator,
OrderedHashSet>::MoveNext();
MoveNext and Seek are private, which makes it unlikely they'll be needed outside
of objects.cc, I think you should be able to safely leave them out.

https://codereview.chromium.org/238063009/diff/1/src/objects.cc#newcode16788
src/objects.cc:16788: EXPLICIT_INSTANTIATE_ACCESSOR(JSMapIterator,
OrderedHashMap, table, Object)
Same down here, I don't think you need the accessors.

[arv (Not doing code reviews), 2014-04-16 22:36:26]

Remove explicit instantiation of private and functions in objects-inl.h

[adamk, 2014-04-16 22:48:05]

lgtm, will try one more time

https://codereview.chromium.org/238063009/diff/20001/src/objects-printer.cc
File src/objects-printer.cc (right):

https://codereview.chromium.org/238063009/diff/20001/src/objects-printer.cc#n...
src/objects-printer.cc:795: OrderedHashMap>::OrderedHashTableIteratorPrint(FILE*
out);
I can't imagine you need these

[adamk, 2014-04-17 17:45:45]

Committed patchset #2 manually as r20857 (presubmit successful).