Implement well-known symbol `Symbol.toStringTag`

Implement well-known symbol `Symbol.toStringTag`

BUG=v8:3502

[ziyunfei, 2014-08-11 00:19:04]

The CQ bit was checked by l446240525@gmail.com

[commit-bot: I haz the power, 2014-08-11 00:19:33]

CQ is trying da patch. Follow status at
 https://v8-status.appspot.com/cq/L446240525@gmail.com/461453002/1

[commit-bot: I haz the power, 2014-08-11 00:19:35]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-08-11 00:19:36]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer or
a provisional committer, _not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[ziyunfei, 2014-08-11 00:19:47]

The CQ bit was unchecked by l446240525@gmail.com

[arv (Not doing code reviews), 2014-08-11 14:40:40]

This change as is will break Chrome and NodeJS (and other embedders of V8).

The problem is that the web depends on the O.p.toString behavior for host
objects. For example:

assert(Object.prototype.toString.call(document.body) === '[object
HTMLBodyElement]')

The embedder calls the V8 API FunctionTemplate::SetClassName which is then used.
With this change that class name is now ignored.

Then there is also: v8::Object::ObjectProtoToString which also needs to be
updated:
https://code.google.com/p/chromium/codesearch#chromium/src/v8/src/api.cc&l=3280

https://codereview.chromium.org/461453002/diff/1/src/v8natives.js
File src/v8natives.js (right):

https://codereview.chromium.org/461453002/diff/1/src/v8natives.js#newcode226
src/v8natives.js:226: if(reservedTags.indexOf(builtinTag) === -1){
Can you change this to a switch? We do not want a linear search for all of
these.

[ziyunfei, 2014-08-11 16:17:54]

On 2014/08/11 14:40:40, arv wrote:
> This change as is will break Chrome and NodeJS (and other embedders of V8).
> 
> The problem is that the web depends on the O.p.toString behavior for host
> objects. For example:
> 
> assert(Object.prototype.toString.call(document.body) === '[object
> HTMLBodyElement]')
> 
> The embedder calls the V8 API FunctionTemplate::SetClassName which is then
used.
> With this change that class name is now ignored.
> 
> Then there is also: v8::Object::ObjectProtoToString which also needs to be
> updated:
>
https://code.google.com/p/chromium/codesearch#chromium/src/v8/src/api.cc&l=3280
> 
> https://codereview.chromium.org/461453002/diff/1/src/v8natives.js
> File src/v8natives.js (right):
> 
> https://codereview.chromium.org/461453002/diff/1/src/v8natives.js#newcode226
> src/v8natives.js:226: if(reservedTags.indexOf(builtinTag) === -1){
> Can you change this to a switch? We do not want a linear search for all of
> these.

Many thanks for your review, Erik! But I'm a c++ noobie and don't know how to
change v8::Object::ObjectProtoToString properly, so I have to give up on this :(