Update VM to latest spec. Referencing a name that is imported
from more than one library is no longer a compile-time error.
If one of the sources of an ambiguous reference is a dart library,
the dart library declaration is automatically hidden.
Also fixes a bug where looking up a getter name in a library
found the getter even though the name is filtered out in the
'hide' combinator.
Long-term we should fix the need for repeatedly convert between
the mangled getter and setter names and the untangled name.
Fixes 12915, 12913, 12724.
R=regis@google.com
Review URL: https://codereview.chromium.org//23484020
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@27312 260f80e4-7a28-3924-810f-c04153c831b5
srdjan@google.com