[es6] Implement spec compliant ToPrimitive in the runtime.

[es6] Implement spec compliant ToPrimitive in the runtime.

This is the first step towards a spec compliant ToPrimitive
implementation (and therefore spec compliant ToNumber, ToString,
ToName, and friends).  It adds support for the @@toPrimitive
symbol that was introduced with ES2015, and also adds the new
Symbol.prototype[@@toPrimitive] and Date.prototype[@@toPrimitive]
initial properties.

There are now runtime functions for %ToPrimitive, %ToNumber and
%ToString, which do the right thing and should be used as fallbacks
instead of the hairy runtime.js implementations.  I will do the
same for the other conversion operations mentioned by the spec in
follow up CLs.  Once everything is in place we can look into
optimizing things further, so that we don't always call into the
runtime.

Also fixed Date.prototype.toJSON to be spec compliant.

R=mstarzinger@chromium.org, yangguo@chromium.org
BUG=v8:4307
LOG=y

Committed: https://crrev.com/f6c6d713b4a1bb94457571f9e627ce2dea531b68
Cr-Commit-Position: refs/heads/master@{#30434}

[Benedikt Meurer, 2015-08-28 08:24:29]

bmeurer@chromium.org changed reviewers:
+ mvstanton@chromium.org

[Benedikt Meurer, 2015-08-28 08:24:29]

Yang: Please do overall review.
Michi: Please review compiler changes.
Michael: Please look at code stubs.

[mvstanton, 2015-08-28 08:34:36]

LGTM code stubs.

[Michael Starzinger, 2015-08-28 08:52:13]

LGTM modulo spec changes, didn't verify those.

https://codereview.chromium.org/1306303003/diff/1/src/objects.cc
File src/objects.cc (right):

https://codereview.chromium.org/1306303003/diff/1/src/objects.cc#newcode6017
src/objects.cc:6017: Handle<Object> exoticToPrim;
nit: not likey camelCase here.

https://codereview.chromium.org/1306303003/diff/1/src/objects.cc#newcode6055
src/objects.cc:6055: Handle<String> methodNames[2];
nit: s/methodName/method_names/

[Benedikt Meurer, 2015-08-28 08:54:53]

https://codereview.chromium.org/1306303003/diff/1/src/objects.cc
File src/objects.cc (right):

https://codereview.chromium.org/1306303003/diff/1/src/objects.cc#newcode6017
src/objects.cc:6017: Handle<Object> exoticToPrim;
On 2015/08/28 08:52:13, Michael Starzinger wrote:
> nit: not likey camelCase here.

Done.

https://codereview.chromium.org/1306303003/diff/1/src/objects.cc#newcode6055
src/objects.cc:6055: Handle<String> methodNames[2];
On 2015/08/28 08:52:13, Michael Starzinger wrote:
> nit: s/methodName/method_names/

Done.

[Yang, 2015-08-28 09:00:34]

lgtm.

[Benedikt Meurer, 2015-08-28 09:00:44]

The CQ bit was checked by bmeurer@chromium.org

[Benedikt Meurer, 2015-08-28 09:00:44]

The patchset sent to the CQ was uploaded after l-g-t-m from
mvstanton@chromium.org, mstarzinger@chromium.org
Link to the patchset: https://codereview.chromium.org/1306303003/#ps20001
(title: "Address Michis comments.")

[commit-bot: I haz the power, 2015-08-28 09:00:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1306303003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1306303003/20001

[commit-bot: I haz the power, 2015-08-28 09:21:30]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-08-28 09:21:55]

Patchset 2 (id:??) landed as
https://crrev.com/f6c6d713b4a1bb94457571f9e627ce2dea531b68
Cr-Commit-Position: refs/heads/master@{#30434}

[adamk, 2015-08-28 19:36:14]

adamk@chromium.org changed reviewers:
+ adamk@chromium.org

[adamk, 2015-08-28 19:36:15]

I'd appreciate if someone from the Language team was included on changes like
this. There's some behavior change in this patch that may cause problems on the
web, see below.

https://codereview.chromium.org/1306303003/diff/20001/src/objects.cc
File src/objects.cc (right):

https://codereview.chromium.org/1306303003/diff/20001/src/objects.cc#newcode6020
src/objects.cc:6020: GetMethod(receiver,
isolate->factory()->to_primitive_symbol()), Object);
This is going to change behavior when invoking ToPrimitive on access-checked
objects. Code which would have previously worked will now throw. See
https://code.google.com/p/v8/issues/detail?id=4289 for a similar issue with
@@isConcatSpreadable.

I have a test case demonstrating the problem, will attach it to the bug.