Mark link between (Detached DOM Trees) and Detached DOM Tree as weak.

Mark link between "(Detached DOM Trees)" and "Detached DOM Tree" as weak.

With this fix "(Detached DOM Trees)" will not appear in the retainers tree of a detached tree.

BUG=

[alph, 2014-04-02 14:19:09]

https://codereview.chromium.org/221923006/diff/1/src/heap-snapshot-generator.cc
File src/heap-snapshot-generator.cc (right):

https://codereview.chromium.org/221923006/diff/1/src/heap-snapshot-generator....
src/heap-snapshot-generator.cc:2411: HeapGraphEdge::kWeak,
May be shortcut?

[loislo, 2014-04-02 14:43:09]

On 2014/04/02 14:19:09, alph wrote:
>
https://codereview.chromium.org/221923006/diff/1/src/heap-snapshot-generator.cc
> File src/heap-snapshot-generator.cc (right):
> 
>
https://codereview.chromium.org/221923006/diff/1/src/heap-snapshot-generator....
> src/heap-snapshot-generator.cc:2411: HeapGraphEdge::kWeak,
> May be shortcut?

We shows Shortcut edges in the retainers tree.

[yurys, 2014-04-02 15:19:09]

On 2014/04/02 14:43:09, loislo wrote:
> On 2014/04/02 14:19:09, alph wrote:
> >
>
https://codereview.chromium.org/221923006/diff/1/src/heap-snapshot-generator.cc
> > File src/heap-snapshot-generator.cc (right):
> > 
> >
>
https://codereview.chromium.org/221923006/diff/1/src/heap-snapshot-generator....
> > src/heap-snapshot-generator.cc:2411: HeapGraphEdge::kWeak,
> > May be shortcut?
> 
> We shows Shortcut edges in the retainers tree.

kWeak is type for weak links from the heap while this CL tries deals with links
between synthetic nodes, this is confusing.

[alph, 2014-04-02 17:27:05]

On 2014/04/02 14:43:09, loislo wrote:
> On 2014/04/02 14:19:09, alph wrote:
> >
>
https://codereview.chromium.org/221923006/diff/1/src/heap-snapshot-generator.cc
> > File src/heap-snapshot-generator.cc (right):
> > 
> >
>
https://codereview.chromium.org/221923006/diff/1/src/heap-snapshot-generator....
> > src/heap-snapshot-generator.cc:2411: HeapGraphEdge::kWeak,
> > May be shortcut?
> 
> We shows Shortcut edges in the retainers tree.

That's fine. I don't like idea of dropping the real retaining edges from the
retaining tree.
I'd like to propose another solution. ptal
https://codereview.chromium.org/222443003/

[loislo, 2014-04-03 07:29:13]

On 2014/04/02 17:27:05, alph wrote:
> On 2014/04/02 14:43:09, loislo wrote:
> > On 2014/04/02 14:19:09, alph wrote:
> > >
> >
>
https://codereview.chromium.org/221923006/diff/1/src/heap-snapshot-generator.cc
> > > File src/heap-snapshot-generator.cc (right):
> > > 
> > >
> >
>
https://codereview.chromium.org/221923006/diff/1/src/heap-snapshot-generator....
> > > src/heap-snapshot-generator.cc:2411: HeapGraphEdge::kWeak,
> > > May be shortcut?
> > 
> > We shows Shortcut edges in the retainers tree.
> 
> That's fine. I don't like idea of dropping the real retaining edges from the
> retaining tree.
> I'd like to propose another solution. ptal
> https://codereview.chromium.org/222443003/

Sounds like we are solving two different problems.

My problem:
In the snapshot we have artificial nodes or "pseudo roots"
that we need for the containment view like "(Detached DOM Trees)" etc.
These nodes don't really exist and do not retain anyone.

In the current implementation we use kInternal edges for the links between
these nodes and their children. It breaks the idea that these "pseudo roots"
don't retain anyone. So I'm trying to fix this.

You problem:
retainers from debugger root that could be solved by your patch.