Clean-up of getCompilationUnit.

Clean-up of getCompilationUnit.

Fixes a few places that assumes libraries can be compilation units.
- VoidElement now belongs to the entry compilation unit of the core library.
- Abstract fields now belong to the compilation unit of the creating accessor.

Committed: https://code.google.com/p/dart/source/detail?r=10711

[Lasse Reichstein Nielsen, 2012-08-15 09:09:12]

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
File lib/compiler/implementation/elements/elements.dart (right):

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
lib/compiler/implementation/elements/elements.dart:201: element = (element as
FunctionElement).patch;
This is still not sufficient to handle all cases, but should allow error
messages to be correct for code in the patch.
Should be modified again when we redo patching.

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
lib/compiler/implementation/elements/elements.dart:703: // compilation unit is
patched.
The current way to handle patched functions will choke on this one because the
getCompilationUnit on the original function will give the patch's compilation
unit.
This needs further work.

[ahe, 2012-08-15 10:00:19]

The use of the cast operator is blocking this issue.

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
File lib/compiler/implementation/elements/elements.dart (right):

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
lib/compiler/implementation/elements/elements.dart:168: enclosingElement !==
null && enclosingElement.isCompilationUnit();
I prefer to not use the short-hand function syntax when it no longer fits on one
line.

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
lib/compiler/implementation/elements/elements.dart:194: return (element as
CompilationUnitOverrideElement).compilationUnit;
Please don't use the cast operator.

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
lib/compiler/implementation/elements/elements.dart:197: return (element as
LibraryElement).entryCompilationUnit;
Please don't use the cast operator.

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
lib/compiler/implementation/elements/elements.dart:200: (element as
FunctionElement).isPatched) {
Please don't use cast operator.

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
lib/compiler/implementation/elements/elements.dart:201: element = (element as
FunctionElement).patch;
Please don't use the cast operator.

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
lib/compiler/implementation/elements/elements.dart:703: // compilation unit is
patched.
On 2012/08/15 09:09:12, Lasse Reichstein Nielsen wrote:
> The current way to handle patched functions will choke on this one because the
> getCompilationUnit on the original function will give the patch's compilation
> unit.
> This needs further work.

Is that coming?

[Lasse Reichstein Nielsen, 2012-08-15 11:17:05]

Fixed comments. 
Removed more "as" casts elsewhere, just on general principle.
Changed getCompilationUnit so that calling it on a patched function directly
gives the original compilation unit of the patchee, but traversing the chain
from below will skip to the patch function's compilation unit.
It's probably still too simplistic. We need some model where the patch function
is only visible to the body of the function, not everywhere else.

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
File lib/compiler/implementation/elements/elements.dart (right):

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
lib/compiler/implementation/elements/elements.dart:168: enclosingElement !==
null && enclosingElement.isCompilationUnit();
On 2012/08/15 10:00:19, ahe wrote:
> I prefer to not use the short-hand function syntax when it no longer fits on
one
> line.

Done.

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
lib/compiler/implementation/elements/elements.dart:194: return (element as
CompilationUnitOverrideElement).compilationUnit;
On 2012/08/15 10:00:19, ahe wrote:
> Please don't use the cast operator.

Done.

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
lib/compiler/implementation/elements/elements.dart:197: return (element as
LibraryElement).entryCompilationUnit;
On 2012/08/15 10:00:19, ahe wrote:
> Please don't use the cast operator.

Done.

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
lib/compiler/implementation/elements/elements.dart:200: (element as
FunctionElement).isPatched) {
On 2012/08/15 10:00:19, ahe wrote:
> Please don't use cast operator.

Done.

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
lib/compiler/implementation/elements/elements.dart:201: element = (element as
FunctionElement).patch;
On 2012/08/15 10:00:19, ahe wrote:
> Please don't use the cast operator.

Done.

https://chromiumcodereview.appspot.com/10834330/diff/1/lib/compiler/implement...
lib/compiler/implementation/elements/elements.dart:703: // compilation unit is
patched.
It's being worked on as a separate change.

[ahe, 2012-08-15 11:32:40]

lgtm