Allow named parameters in const constructor invocations.

Allow named parameters in const constructor invocations.

The compile time constant analyzer visited the name of the parameter as identifier, which was not resolved. This resulted in an element of kind NONE, which was classified as non-constant.

BUG=http://code.google.com/p/dart/issues/detail?id=1576
TEST=language/NamedArgumentInConstCreationTest

Committed: https://code.google.com/p/dart/source/detail?r=4301

[karlklose, 2012-02-15 10:27:51]

The name part of the named expression representing the named argument was
visited as unresolved identifier, which is considered a non-constant.

[zundel, 2012-02-15 13:16:10]

lgtm