Migrates some resolver errors to parser stage

Migrates some resolver errors to parser stage

I found some resolver errors I could not reproduce because they were
not reachable code (parser wouldn't accept them).  Since we have discussed 
running the analysis server in stages where parsing might be done first, 
it made sense to me to move some error reporting into the parser anywy.  
I also tried to make the messages more friendly.

Committed: https://code.google.com/p/dart/source/detail?r=9361

[Brian Wilkerson, 2012-07-03 16:06:37]

LGTM

https://chromiumcodereview.appspot.com/10690074/diff/1/compiler/java/com/goog...
File compiler/java/com/google/dart/compiler/parser/ParserErrorCode.java (right):

https://chromiumcodereview.appspot.com/10690074/diff/1/compiler/java/com/goog...
compiler/java/com/google/dart/compiler/parser/ParserErrorCode.java:79:
FACTORY_CANNOT_BE_TOPLEVEL("A factory cannot be toplevel, it must be a member of
a class"),
nit: "toplevel" --> "top level"