https://bugs.webkit.org/show_bug.cgi?id=124230

Reviewed by Timothy Hatcher.

Changed ContentFlowTreeContentView to use one DOMTreeOutline by just
populating it with root DOMTreeElements directly. That is very
similar to how DOMTreeOutline works when omitRootDOMNode is used.

Now that ContentFlowTreeContentView has only one DOMTreeOutline,
it makes sense to change its base class to be DOMTreeContentView instead.
Also, with that I've changed its name to ContentFlowDOMTreeContentView.

I had to move all the DOMTree document loading code from DOMTreeContentView to a
new class called FrameDOMTreeContentView. This is used to display the DOM of the
frame objects. FrameDOMTreeContentView is also inheriting from DOMTreeContentView.

Issues that are fixed as a side effect:
- Selection path components are now displaying all the sibling elements for contentFlow.contentNodes
(those are the nodes that have "-webkit-flow-into" set directly).
- Keyboard navigation works for the contentFlow.contentNodes.
- Search is implemented in DOMTreeContentView, so that code now works for flows too.
The DOMAgents's search API will use all the Documents to lookup for nodes, so it might
find DOM nodes that are not part of the flow. This is in line with the behavior for the
frames.

* UserInterface/ContentFlowDOMTreeContentView.js: Renamed from ContentFlowTreeContentView
to better reflect the inheritance from DOMTreeContentView.
(WebInspector.ContentFlowDOMTreeContentView):
(WebInspector.ContentFlowDOMTreeContentView.prototype.closed):
(WebInspector.ContentFlowDOMTreeContentView.prototype._createContentTrees):
(WebInspector.ContentFlowDOMTreeContentView.prototype._contentNodeWasAdded):
(WebInspector.ContentFlowDOMTreeContentView.prototype._contentNodeWasRemoved):
* UserInterface/ContentView.js:
(WebInspector.ContentView):
* UserInterface/DOMTreeContentView.js:
(WebInspector.DOMTreeContentView):
(WebInspector.DOMTreeContentView.prototype.closed):
(WebInspector.DOMTreeContentView.prototype.):
(WebInspector.DOMTreeContentView.prototype._restoreSelectedNodeAfterUpdate):
(WebInspector.DOMTreeContentView.prototype._selectedNodeDidChange):
* UserInterface/FrameDOMTreeContentView.js: Added.
(WebInspector.FrameDOMTreeContentView):
(WebInspector.FrameDOMTreeContentView.prototype.get domTree):
(WebInspector.FrameDOMTreeContentView.prototype.closed):
(WebInspector.FrameDOMTreeContentView.prototype._rootDOMNodeAvailable):
(WebInspector.FrameDOMTreeContentView.prototype._rootDOMNodeInvalidated):
(WebInspector.FrameDOMTreeContentView.prototype._requestRootDOMNode):
* UserInterface/Main.html:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@159151 268f45cc-cd09-0410-ab3c-d52691b4dbfc