Support symbol-named properties in API

Support symbol-named properties in API

Add new "Name" type to API that is a supertype of Symbol and String.

Object::SetDeclaredAccessor, Object::SetAccessorProperty, Template::Set,
Template::SetAccessorProperty, and Template::SetDeclaredAccessor now
take a Name as the property name instead of a String.

Add Object::SetAccessor, Template::SetNativeDataProperty, and
ObjectTemplate::SetAccessor overloads that can define accessors for
symbol-named properties.

R=dcarney@chromium.org, rossberg@chromium.org
BUG=v8:3394
TEST=cctest/test-api/TestSymbolProperties
LOG=Y

Committed: https://code.google.com/p/v8/source/detail?r=23247

[wingo, 2014-08-12 12:12:03]

The bulk of the changes in this patch are to the API layer.  They are compatible
changes.

Internally, I changed use of AccessorGetterCallback to use
AccessorNameGetterCallback, and the same for the setters.  (The difference is
that the one with Name passes the name as a Name, whereas the other one passes
it as a string.)  These should be compatible -- although calling an
AccessorGetterCallback as if it were an AccessorNameGetterCallback isn't
strictly C++-legal, AFAIU, I don't think there are problems with V8's targets,
and this minifies the change to the code generator.

[wingo, 2014-08-12 12:19:44]

I should also mention that I didn't "git cl format" on this one, as it caused
too many lines to change.  If the commit is approved, I can format the CL before
landing.

[dcarney, 2014-08-12 18:01:27]

lgtm

[rossberg, 2014-08-19 11:19:27]

lgtm

https://codereview.chromium.org/459413002/diff/40001/src/api.cc
File src/api.cc (left):

https://codereview.chromium.org/459413002/diff/40001/src/api.cc#oldcode3420
src/api.cc:3420: Setter getter,
OMG...

[wingo, 2014-08-20 15:25:38]

Committed patchset #2 manually as 23247.