Improve printing for Symbols.

Improve printing for Symbols.

Private symbols we create in the heap don't have names, but we can
resolve them to a constant string.

This gives handy debugger output like:

(gdb) job 0x2020c67d
0x2020c67d: [Symbol]
 - hash: 547385396
 - name: 0x20208091 <undefined> (uninitialized_symbol)
 - private: 1
 - own: 1
$7 = void
(gdb)

or with ShortPrint() in an array:

...
  [5]: 0x2020c67d <Symbol: 547385396 (uninitialized_symbol)>
...

Printing help for internal symbols

R=yangguo@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=24869

[mvstanton, 2014-10-24 11:28:05]

Hi Yang,
Another bit of trivia, nicer printing for symbols.
thx again,
--Michael

[Yang, 2014-10-24 11:33:14]

On 2014/10/24 11:28:05, mvstanton wrote:
> Hi Yang,
> Another bit of trivia, nicer printing for symbols.
> thx again,
> --Michael

lgtm.

[mvstanton, 2014-10-24 12:36:54]

Committed patchset #1 (id:1) manually as 24869 (presubmit successful).