Enable ES6 Symbols by default

Enable ES6 Symbols by default

In doing so also remove all references to the --harmony-symbols flag.
Due to the way context snapshotting works, it's not possible to simply enable
the flag by default.

BUG=v8:2158
LOG=Y
R=dslomov@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=22831

[adamk, 2014-07-28 23:15:55]

Note that this is a necessary step for enabling Maps and Sets as well (which
I've uploaded at https://codereview.chromium.org/427723002)

[danno, 2014-07-29 08:18:04]

FYI, Andreas is on vacation until Thursday, so it will be a day or two until he
can review this.

[adamk, 2014-08-01 21:36:38]

Review ping? Would like to get these some bake time in Canary before the branch
point.

[Dmitry Lomov (no reviews), 2014-08-01 21:58:27]

lgtm

[Dmitry Lomov (no reviews), 2014-08-01 21:58:28]

lgtm

[adamk, 2014-08-01 22:08:06]

On 2014/08/01 at 21:58:28, dslomov wrote:
> lgtm

Thanks. Looks like I should wait to land, though, due to tree throttling.

[adamk, 2014-08-04 18:18:06]

Committed patchset #1 manually as 22831 (presubmit successful).

[rossberg, 2014-08-04 19:32:15]

Hi Adam, sorry, I had my vacation extended by 2 days.

I actually had the same CL finished before my vacation, but couldn't land it:

https://codereview.chromium.org/405803006/

From a cursory look it seems they are equivalent. :)

[adamk, 2014-08-04 19:47:14]

On 2014/08/04 at 19:32:15, rossberg wrote:
> Hi Adam, sorry, I had my vacation extended by 2 days.
> 
> I actually had the same CL finished before my vacation, but couldn't land it:
> 
> https://codereview.chromium.org/405803006/
> 
> From a cursory look it seems they are equivalent. :)

Ah, I didn't see that one, sorry for the duplication. I put together this one to
unblock enabling Maps/Sets.