This moves input.dart to editing2/, since that way we can define the layering as strictly unidirectional.
It also reorders a bunch of imports to fit the style guide.
I removed the old remnants of the widgets example, and put the fn2 examples into the examples/widgets/ directory, to parallel the framework directory names.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1177243002.

The final animation is more involved, but this CL starts implementing the menu
animation by making it fade in.

R=ianh@google.com

Review URL: https://codereview.chromium.org/1174253003.

R=abarth@chromium.org, abarth, hansmuller

Review URL: https://codereview.chromium.org/1181533003

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

Review URL: https://codereview.chromium.org/1174203002

This lays the groundwork for using fn widgets in static environments.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1178703002

Dispatch events to fn nodes for each RenderObject that the event goes through, instead of starting at the innermost target and just propagating through our tree.
This starts laying the groundwork for fn disconnected subtrees that are linked together into one RenderObject tree.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1181503002

These are now called Block, Stack, and Flex, respectively. Less verbose.

R=jackson@google.com, ianh@google.com

Review URL: https://codereview.chromium.org/1181533002.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1181453003

Turns out that reintroducing the field in each subclass is probably allocating more storage per node. So let's not do that.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1177483004

Previously, they always started at the center of the RenderInkWell. Now we
remember the local coordinates we computed during the hit test and provide that
information when handling the event.

R=ianh@google.com

Review URL: https://codereview.chromium.org/1180553002.

In general, we are hugely inconsistent in what onFoo/onFoo() means.
I'm cleaning out all the cases where onFoo() is a method.

Also, this fixes EditableText, which got missed in the recent syncFields() pass.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1175753003

We can use const [] instead and we'll be sure we don't mutate this constant.

R=ianh@google.com

Review URL: https://codereview.chromium.org/1178623002.

This also removes one bit of magic to make it more obvious what on is
going on during a sync, which should hopefully help.

Components have to decide if they support being stateful or not. If
they do, then they must implement syncFields() and have mutable
fields; if they don't, then they must have final fields. This isn't
particularly enforced, though.

This also renames _willSync() to _retainStatefulNodeIfPossible(), for
clarity, and fixes some minor style issues and one typo that was
breaking the drawer.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1174023003

I accidentally removed two lines of code in https://codereview.chromium.org/1172173002 when merging upsteam before landing.

TBR=abarth

Review URL: https://codereview.chromium.org/1171163005

 - constructors first
 - have either a blank line at the top and bottom of each class, or no blank line in either place (it's still inconsistent about which we should do)
 - hide clamp()

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1172173002

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1174683005

Also considered "AnnotationNode", "LabelNode", "BadgeNode", but "TagNode" seemed simplest.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1169853008

This would cause them to forget what the most recent child they'd been given was, with disastrous effects later.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1173683003

The FlexExpandingChild flex parameter is now a keyword as
well, which adds a small readability benefit.

R=ianh@google.com

Review URL: https://codereview.chromium.org/1172503004.

This CL pulled an implementation of position: absolute in RenderStackContainer.

R=eseidel@chromium.org, ianh@google.com

Review URL: https://codereview.chromium.org/1166363002.

The popup menu in the stocks app is supposed to size its width to the max
intrinsic width of the menu. This CL teaches it how to do that.

It's a shame that we need to ceilToDouble the output of RenderParagraph. If we
don't do that, we run into floating point layout trouble and the menu triggers
a line break. The correct fix is to do layout in fixed point.

R=ianh@google.com

Review URL: https://codereview.chromium.org/1168113005

Also change SizedBox.

This makes the code that uses Container() and SizedBox() much more readable.

The underlying RenderSizedBox is not affected by this change.

R=abarth@chromium.org, eseidel@chromium.org

Review URL: https://codereview.chromium.org/1166203002

R=abarth@chromium.org, abarth

Review URL: https://codereview.chromium.org/1164363002

The popup menu is displayed in the wrong location with the wrong width, but it
does draw. I've also removed the checkbox because the flex container was
causing me trouble.  I'll add it back in a later CL.

R=ianh@google.com

Review URL: https://codereview.chromium.org/1166153002

This CL is the first step towards getting PopupMenuItem working in fn2. We
introduce the ability to add a minWidth to a Container by creating a
RenderConstrainedBox class to apply the new constraints.

R=ianh@google.com

Review URL: https://codereview.chromium.org/1155683011

This includes making SizedBox default to infinite size, and making
Container default to containing one infinite-sized SizedBox. That way,
you can use an empty Container as a spacer in a flex box.

The rendering doesn't quite work, because of a bug in flex whereby it
doesn't shrink-wrap its contents in the cross-direction, it fills the
parent. Collin is on that.

R=jackson@google.com

Review URL: https://codereview.chromium.org/1163633003

TBR=abarth

Review URL: https://codereview.chromium.org/1169543009

Changes:
- Remove all the old tracing logic since that was a lot of code for
  just random printf debugging and nobody seems to use it
- Convert "defunct", a permanent state transition, to "mounted", a
  state that can be entered and exitted arbitrarily
- Coallesce mount/unmount notifications so there's only one per frame
- Remove handleRemoved() since we don't use it
- Rename a local variable 'parent' to 'ancestor' to avoid shadowing
  the field
- Replace uses of forEach() with for-in

Effects:
- Reusing a node provided to a constructor in a new place in a tree
  (especially at a different depth) no longer fails (it used to fail
  because the node would be marked defunct then remounted later, at
  which point it would fail)

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1169673002

Export Point, Size, Rect, Color, Paint, Path, BoxDecoration, Border, BorderSide, EdgeDims, and FlexDirection from fn2.dart
That way most of our libraries don't have to use sky.Foo all over the place, and we can reduce the number of imports in most Dart components.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1161323004

 - several places where we use a getter knowing that it will return a
   subclass of its declared type, even asserting that it does, but
   where the analyzer is worried that the getter might start returning
   a new value unexpectedly, solved by having a temporary local
   variable shadow the getter and asserting that it doesn't change
   value
 - many many places where we do this with parentData specifically,
   solved by type-erasing parentData.
 - a place where a mixin wants to be subclassing another class, and
   uses its methods, solved by saying that the mixin is abstract but
   implements the superclass

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1160923008

Turns out Scaffold needs to hook _remove, so we need to rename it to remove to
expose it outside fn2.dart.

R=ianh@google.com

Review URL: https://codereview.chromium.org/1160013007

R=abarth@chromium.org, eseidel@chromium.org, abarth

Review URL: https://codereview.chromium.org/1157573012

Improve the RenderObject.toString() logic so that there's not blank lines everywhere and to generally be better.
Adds sizes, positions, transforms, improves RenderParagraph's output.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1160233004

We should be asserting that old.root is a ContainerRenderObjectMixin because
we're able to manipulate its child list.

R=ianh@google.com

Review URL: https://codereview.chromium.org/1169593002

R=eseidel@chromium.org

Review URL: https://codereview.chromium.org/1162623011

This CL makes FixedHeightScrollable able to measure heights. In the DOM-based
version, FixedHeightScrollable forced a synchronous layout in a microtask in
order to measure the size of itself and its children. In the DOM-less version,
we now require the subclass to tell us the item height and we measure our own
height using a layout callback.

R=ianh@google.com

Review URL: https://codereview.chromium.org/1161063005

https://www.dartlang.org/articles/style-guide/#names

R=jackson@google.com

Review URL: https://codereview.chromium.org/1158813004

In the future, we might want to extend this class to clip to a configurable
rect in addition to clipping to its bounds.

R=eseidel@chromium.org, ianh@google.com

Review URL: https://codereview.chromium.org/1145263006

Rename OneChildListRenderObjectWrapper to MultiChildRenderObjectWrapper to avoid the confusing similarity with OneChildRenderObjectWrapper.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1150543005

TBR=ianh@google.com

Review URL: https://codereview.chromium.org/1164073002