Remove json2 JS script and the try except around seal

[nickva]

• Remove json2 all supported runtimes have the JSON object now

• Remove the try except for broken seal in 1.9.x we don't support 1.9.x and it worked in 1.8.x and then in 60+ (at least, we don't support anything lower).

1.8.5

% js --help 2>&1 | grep 185
  185:  JavaScript 1.8.5 (default)
% js
js>  var a=[1,2,3]; Object.freeze(a); a[1]=100; a
[1, 2, 3]

78

% js78
var a=[1,2,3]; Object.freeze(a); a[1]=100; a
[1, 2, 3]
js>

[1] https://bugzilla.mozilla.org/show_bug.cgi?id=449657#c0

[nickva]

Tested it locally with 1.8.5 ./configure --dev --spidermonkey-version 1.8.5 and make check

[big-r81]

Tested it locally with 91 ./configure --dev --spidermonkey-version 91 and make check

Collections
===========

     Total    Fixture       Test      Count     Failed     Errors    Skipped
    777.5s     322.6s     454.9s       3250          0          0          0 EUnit        
    168.4s       0.0s     168.4s        538          0          0          8 EXUnit        
      0.0s       0.0s       0.0s          0          0          0          0 JavaScript        
      0.0s       0.0s       0.0s          0          0          0          0 Mango