dart2js cps: Remove dart2dart from cps pipeline and clean up.

dart2js cps: Remove dart2dart from cps pipeline and clean up.

Removing dart2dart stuff is the most radical change, but there's also
a bunch of general clean up, some of it somewhat unrelated, but long
overdue.

I've focused on making the IR easier to read end-to-end.

For instance, I've stripped out a complicated assertion on InvokeMethod,
because it is distracting and hasn't paid off. AFAIK it never caught a
single bug, but a few times it has spuriously failed and needed
patching.

Some notable changes in the IR:
- Removed FieldDefinition, ConstructorDefinition, Initializers.
- Removed RootNode. There was only one subclass left.
- Removed Body. Has been inlined into FunctionDefinition.
- MutableVariable can no longer be a function parameter.
- Removed default parameter values and local constants from the IR.

I decided to keep nested functions for the time being because there is
a slight chance they might come in handy for async/await.
I'm not sure yet. We can strip them out later if they are not needed.

I've also left the subclassing JsIrBuilder <: IrBuilder for now,
even though the classes could be merged. Same with the visitor.

BUG=
R=kmillikin@google.com

Committed: https://github.com/dart-lang/sdk/commit/ac4ab2b5b7472e83d2112c8e1d0473541c7237a4

[asgerf, 2015-05-29 13:06:03]

asgerf@google.com changed reviewers:
+ kmillikin@google.com

[asgerf, 2015-05-29 13:06:03]

asgerf@google.com changed required reviewers:
+ kmillikin@google.com

[Kevin Millikin (Google), 2015-05-29 14:09:17]

This is seriously very nice.  LGTM.

It will conflict with changes in flight, but I don't see a good way to avoid
that and it's long overdue, so I'd vote in favor of just landing it.

https://codereview.chromium.org/1155463005/diff/1/pkg/compiler/lib/src/cps_ir...
File pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart (right):

https://codereview.chromium.org/1155463005/diff/1/pkg/compiler/lib/src/cps_ir...
pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart:830: /// Create a
[ir.FunctionDefinition] for [element] using [_root] as the body.
element is state.currentElement.

[asgerf, 2015-05-29 14:18:03]

https://codereview.chromium.org/1155463005/diff/1/pkg/compiler/lib/src/cps_ir...
File pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart (right):

https://codereview.chromium.org/1155463005/diff/1/pkg/compiler/lib/src/cps_ir...
pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart:830: /// Create a
[ir.FunctionDefinition] for [element] using [_root] as the body.
On 2015/05/29 14:09:17, Kevin Millikin (Google) wrote:
> element is state.currentElement.

Done.

[asgerf, 2015-05-29 15:39:06]

Committed patchset #4 (id:60001) manually as
ac4ab2b5b7472e83d2112c8e1d0473541c7237a4 (presubmit successful).