dart2dart: Support for inner functions in new IR.

dart2dart: Support for inner functions in new IR.

In CPS, closure variables are modeled as ref cells. In tree, variables
are in scope within inner functions and closure variables are handled directly.

In Dart, a function must be declared if it has a return type or is recursive.
Therefore tree now has both FunctionExpression and FunctionDeclaration, the latter
is mainly to be used for functions that cannot occur in expression context.

The CPS also has two ways of creating functions, CreateFunction and DeclareFunction,
but here the latter is only strictly necessary for recursive function.

The CL also contains quite a bit of other code improvements that came along.

BUG=
R=kmillikin@google.com, sigurdm@google.com

Committed: https://code.google.com/p/dart/source/detail?r=38005

[sigurdm, 2014-07-02 14:29:20]

Just a few style nits.
Lgtm.

https://codereview.chromium.org/366853007/diff/1/sdk/lib/_internal/compiler/i...
File sdk/lib/_internal/compiler/implementation/dart_backend/dart_tree.dart
(right):

https://codereview.chromium.org/366853007/diff/1/sdk/lib/_internal/compiler/i...
sdk/lib/_internal/compiler/implementation/dart_backend/dart_tree.dart:897: // in
expression context (currently only the case for FunctionDeclarations)
Comment missing full stop

https://codereview.chromium.org/366853007/diff/1/sdk/lib/_internal/compiler/i...
File sdk/lib/_internal/compiler/implementation/ir/ir_builder.dart (right):

https://codereview.chromium.org/366853007/diff/1/sdk/lib/_internal/compiler/i...
sdk/lib/_internal/compiler/implementation/ir/ir_builder.dart:992: ir.Primitive
continueWithExpression(ir.Expression build(ir.Continuation k)) {
Nice!

https://codereview.chromium.org/366853007/diff/1/sdk/lib/_internal/compiler/i...
File sdk/lib/_internal/compiler/implementation/ir/ir_nodes.dart (right):

https://codereview.chromium.org/366853007/diff/1/sdk/lib/_internal/compiler/i...
sdk/lib/_internal/compiler/implementation/ir/ir_nodes.dart:324: /// There may
not exist a [SetClosureVariable] to [variable].
I guess it is clearer to write
/// There must not exist a [SetClosureVariable] to [variable].

https://codereview.chromium.org/366853007/diff/1/tests/language/closure_varia...
File tests/language/closure_variable_shadow_test.dart (right):

https://codereview.chromium.org/366853007/diff/1/tests/language/closure_varia...
tests/language/closure_variable_shadow_test.dart:7: // The intermediate variable
'y' must either be preserved or parameters must be renamed.
Long line

[asgerf, 2014-07-02 14:35:32]

https://codereview.chromium.org/366853007/diff/1/sdk/lib/_internal/compiler/i...
File sdk/lib/_internal/compiler/implementation/dart_backend/dart_tree.dart
(right):

https://codereview.chromium.org/366853007/diff/1/sdk/lib/_internal/compiler/i...
sdk/lib/_internal/compiler/implementation/dart_backend/dart_tree.dart:897: // in
expression context (currently only the case for FunctionDeclarations)
On 2014/07/02 14:29:20, sigurdm wrote:
> Comment missing full stop

Done.

https://codereview.chromium.org/366853007/diff/1/sdk/lib/_internal/compiler/i...
File sdk/lib/_internal/compiler/implementation/ir/ir_nodes.dart (right):

https://codereview.chromium.org/366853007/diff/1/sdk/lib/_internal/compiler/i...
sdk/lib/_internal/compiler/implementation/ir/ir_nodes.dart:324: /// There may
not exist a [SetClosureVariable] to [variable].
On 2014/07/02 14:29:20, sigurdm wrote:
> I guess it is clearer to write
> /// There must not exist a [SetClosureVariable] to [variable].

You're right, thanks.

https://codereview.chromium.org/366853007/diff/1/tests/language/closure_varia...
File tests/language/closure_variable_shadow_test.dart (right):

https://codereview.chromium.org/366853007/diff/1/tests/language/closure_varia...
tests/language/closure_variable_shadow_test.dart:7: // The intermediate variable
'y' must either be preserved or parameters must be renamed.
On 2014/07/02 14:29:20, sigurdm wrote:
> Long line

Done.

[Kevin Millikin (Google), 2014-07-04 09:00:21]

OK, LGTM.

[asgerf, 2014-07-04 10:09:30]

Committed patchset #3 manually as r38005 (presubmit successful).