Implicit lambda fails to compile in return statement.

Imported from http://bugzilla.roxen.com/bugzilla/show_bug.cgi?id=3650

Reported by Marcus Agehall agehall@roxen.com

When using an implicit lambda like this:

return foo() { ... };

the compiler fails to compile the code. Changing the code to

mixed ret=foo() { ... };
return ret;

compiles.