Add LayoutRoot

Make it possible to draw Text in the new window/document-less world

I had to add back document.createText() since new Text()
does not work in the new world yet.

LayoutRoot is a new Dart-exposed class which holds the Frame and
all associated machinery, sufficient to trigger a restyle
and layout of the subtree.

This is all kinda hacky and I'm sure likely to cause many
crashes if folks call random methods on these disconnected
trees.

But this makes it at least possible to paint text for now
and we can improve this in the coming days.

This really should have Adam's review.  It's hugely hacky
but I'd like to negotiate out with him the timeline on
which we should fix some of these hacks.

TBR=abarth@chromium.org
R=ianh@google.com

[eseidel, 2015-05-26 17:50:44]

eseidel@chromium.org changed reviewers:
+ ianh@google.com

[Hixie, 2015-05-26 18:07:16]

lgtm

This is great. We should figure out what the eventual API will look like and
then chip away at this until that's what we have left.

https://codereview.chromium.org/1148253003/diff/40001/sky/engine/core/frame/F...
File sky/engine/core/frame/FrameHost.cpp (right):

https://codereview.chromium.org/1148253003/diff/40001/sky/engine/core/frame/F...
sky/engine/core/frame/FrameHost.cpp:77: //    return
m_page->deviceScaleFactor();
this is exciting. What does it mean?

https://codereview.chromium.org/1148253003/diff/40001/sky/engine/core/frame/F...
File sky/engine/core/frame/FrameView.cpp (right):

https://codereview.chromium.org/1148253003/diff/40001/sky/engine/core/frame/F...
sky/engine/core/frame/FrameView.cpp:267: //ASSERT(m_frame->page());
why just commented out?

https://codereview.chromium.org/1148253003/diff/40001/sky/examples/spinning_a...
File sky/examples/spinning_arabic.dart (right):

https://codereview.chromium.org/1148253003/diff/40001/sky/examples/spinning_a...
sky/examples/spinning_arabic.dart:23: layoutRoot.layout();
Why do you layout() on the layoutRoot, but paint() on the layoutRoot.rootElement
?

[eseidel, 2015-05-26 19:13:05]

https://codereview.chromium.org/1148253003/diff/40001/sky/engine/core/frame/F...
File sky/engine/core/frame/FrameHost.cpp (right):

https://codereview.chromium.org/1148253003/diff/40001/sky/engine/core/frame/F...
sky/engine/core/frame/FrameHost.cpp:77: //    return
m_page->deviceScaleFactor();
On 2015/05/26 at 18:07:16, Hixie wrote:
> this is exciting. What does it mean?

This is probably wrong.

https://codereview.chromium.org/1148253003/diff/40001/sky/engine/core/frame/F...
File sky/engine/core/frame/FrameView.cpp (right):

https://codereview.chromium.org/1148253003/diff/40001/sky/engine/core/frame/F...
sky/engine/core/frame/FrameView.cpp:267: //ASSERT(m_frame->page());
On 2015/05/26 at 18:07:16, Hixie wrote:
> why just commented out?

Probably could be removed now.

https://codereview.chromium.org/1148253003/diff/40001/sky/engine/core/paintin...
File sky/engine/core/painting/LayoutRoot.idl (right):

https://codereview.chromium.org/1148253003/diff/40001/sky/engine/core/paintin...
sky/engine/core/painting/LayoutRoot.idl:6: ]interface LayoutRoot {
Missing space.

https://codereview.chromium.org/1148253003/diff/40001/sky/examples/spinning_a...
File sky/examples/spinning_arabic.dart (right):

https://codereview.chromium.org/1148253003/diff/40001/sky/examples/spinning_a...
sky/examples/spinning_arabic.dart:23: layoutRoot.layout();
On 2015/05/26 at 18:07:16, Hixie wrote:
> Why do you layout() on the layoutRoot, but paint() on the
layoutRoot.rootElement ?

No good reason.  I can trivially add paint() to the layout root object.

[eseidel, 2015-05-27 18:06:30]

Landed as 10892aee0f377cfd7431da9b834e65ca112858cc.