ES6 symbols: implement name property

ES6 symbols: implement name property

Adds string-valued name property to symbols, and uses it for pretty-printing.

Requires allocating symbols in pointer space, with a custom iterator to skip the unboxed hash.

R=mstarzinger@chromium.org
BUG=

Committed: http://code.google.com/p/v8/source/detail?r=14053

[Michael Starzinger, 2013-03-22 12:03:24]

LGTM if comments are addressed.

https://codereview.chromium.org/12459026/diff/2002/src/objects.cc
File src/objects.cc (right):

https://codereview.chromium.org/12459026/diff/2002/src/objects.cc#newcode1467
src/objects.cc:1467:
String::cast(symbol->name())->StringShortPrint(accumulator);
I think there is a white-space missing between the hash and the name in the
printout.

https://codereview.chromium.org/12459026/diff/2002/src/objects.h
File src/objects.h (right):

https://codereview.chromium.org/12459026/diff/2002/src/objects.h#newcode7401
src/objects.h:7401: DECL_ACCESSORS(name, Object)
Maybe it might make sense to add a short one-line comment of what the semantics
of this field are, e.g.:

// [name]: The string representation of this symbol or undefined.

https://codereview.chromium.org/12459026/diff/2002/src/runtime.cc
File src/runtime.cc (right):

https://codereview.chromium.org/12459026/diff/2002/src/runtime.cc#newcode688
src/runtime.cc:688: Handle<Object> name(args[0], isolate);
If you use the following instead, you can get by without allocating a handle and
hence with a NoHandleAllocation scope instead.

Handle<Object> name = args.at<Object>(0);

We might even support the following by now, not sure though. I would prefer the
second if possible.

CONVERT_ARG_HANDLE_CHECKED(Object, name, 0);

https://codereview.chromium.org/12459026/diff/2002/src/symbol.js
File src/symbol.js (right):

https://codereview.chromium.org/12459026/diff/2002/src/symbol.js#newcode45
src/symbol.js:45: throw new $TypeError("Symbol.prototype.name is not generic");
Use MakeTypeError here, see my comments in the previous CL about this.

[rossberg, 2013-03-22 13:02:41]

https://codereview.chromium.org/12459026/diff/2002/src/objects.cc
File src/objects.cc (right):

https://codereview.chromium.org/12459026/diff/2002/src/objects.cc#newcode1467
src/objects.cc:1467:
String::cast(symbol->name())->StringShortPrint(accumulator);
On 2013/03/22 12:03:25, Michael Starzinger wrote:
> I think there is a white-space missing between the hash and the name in the
> printout.

That actually was intentional, but I added a space anyway. :)

https://codereview.chromium.org/12459026/diff/2002/src/objects.h
File src/objects.h (right):

https://codereview.chromium.org/12459026/diff/2002/src/objects.h#newcode7401
src/objects.h:7401: DECL_ACCESSORS(name, Object)
On 2013/03/22 12:03:25, Michael Starzinger wrote:
> Maybe it might make sense to add a short one-line comment of what the
semantics
> of this field are, e.g.:
> 
> // [name]: The string representation of this symbol or undefined.

Done.

https://codereview.chromium.org/12459026/diff/2002/src/runtime.cc
File src/runtime.cc (right):

https://codereview.chromium.org/12459026/diff/2002/src/runtime.cc#newcode688
src/runtime.cc:688: Handle<Object> name(args[0], isolate);
On 2013/03/22 12:03:25, Michael Starzinger wrote:
> If you use the following instead, you can get by without allocating a handle
and
> hence with a NoHandleAllocation scope instead.
> 
> Handle<Object> name = args.at<Object>(0);
> 
> We might even support the following by now, not sure though. I would prefer
the
> second if possible.
> 
> CONVERT_ARG_HANDLE_CHECKED(Object, name, 0);

Done.

https://codereview.chromium.org/12459026/diff/2002/src/symbol.js
File src/symbol.js (right):

https://codereview.chromium.org/12459026/diff/2002/src/symbol.js#newcode45
src/symbol.js:45: throw new $TypeError("Symbol.prototype.name is not generic");
On 2013/03/22 12:03:25, Michael Starzinger wrote:
> Use MakeTypeError here, see my comments in the previous CL about this.

Done.