Named optional parameter can begin with an underscore

[DartBot]

This issue was originally filed by alexei.kaigo...@gmail.com

---

Dart Language specification reads:
6.2.2 Named Optional Formals
 It is a compile-time error if the name of a named optional parameter begins with an _ character.

However, dart_bin reports no error in such cases.

What steps will reproduce the problem?

1. create test file:
   main() {
     void func([var _x]) {}
   }
2. run it with dart/out/Debug_ia32/dart_bin
3. check returned error code

What is the expected output? What do you see instead?
compiler error expected, but no error reported

What version of the product are you using? On what operating system?
dart svn revision 1499, on Linux

Please provide any additional information below.:

This error causes failure of the test
co19/LangSpecTest/06_Functions/06_2_Formal_Parameters/06_2_2_Named_Optional_Formals/A03/t01

[DartBot]

This comment was originally written by drfibonacci@google.com

---

Added Area-VM, Triaged labels.

[iposva-google]

Set owner to @mhausner.
Added Accepted label.

[DartBot]

This comment was originally written by @mhausner

---

Fixed at r5444.

---

Added Fixed label.

The spec is under discussion, reopen the bug as a language issue.

---

Removed the owner.
Removed Area-VM label.
Added Area-Language, Triaged labels.

Issue #1012 has been merged into this issue.

---

Set owner to @mhausner.
Removed Area-Language label.
Added Area-VM, Fixed labels.