Improve ECMA262 Tests

[shiqimei]

Before

Average memory statistics for 75250 tests:

NAME                    COUNT     SIZE
memory allocated         1011   124975  (123.6 per block)
memory used               967   117030  (0 overhead, 8.2 average slack)
atoms                     532    26858  (50.5 per atom)
objects                   172    12425  (72.2 per object)
properties              876    15798  (5.1 per object)
shapes                   60    13809  (230.2 per shape)
bytecode functions         13     1685
bytecode                 13      931  (71.6 per function)
C functions               100
arrays                      1
fast arrays               1
elements                  1       16  (1.0 per fast array)

Result: 515/75250 errors, 1392 excluded, 7972 skipped, 515 new

After

Average memory statistics for 75820 tests:

NAME                    COUNT     SIZE
memory allocated         1015   139033  (137.0 per block)
memory used               971   116989  (0 overhead, 22.7 average slack)
atoms                     536    27003  (50.4 per atom)
objects                   172    12433  (72.3 per object)
  properties              877    15829  (5.1 per object)
  shapes                   60    13821  (230.3 per shape)
bytecode functions         13     1699
  bytecode                 13      975  (75.0 per function)
C functions               100
arrays                      1
  fast arrays               1
  elements                  1       16  (1.0 per fast array)

Result: 1368/75820 errors, 9368 skipped, 1368 new

Actions

1. Lock and freeze test262 commit and make it a submodule, or the total tests count increase time by time, not good for compare test reulsts before/after code changes; We upgrade test262 submodule periodically;
2. Record error test count, warning if code changes introduce new bugs.