When reading a full snapshot use the class id from the snapshot instead of generating a new one. Th…

1. When reading a full snapshot use the class id from the snapshot instead
   of generating a new one. This ensures that assumptions made about the
   class id when generating a snapshot will still hold in the version that
   runs from a snapshot.

2. remove ObjectHistogram code as it is not used anymore and has been replaced
   by VM service.

R=johnmccutchan@google.com, regis@google.com

Committed: https://code.google.com/p/dart/source/detail?r=33340

[regis, 2014-03-05 00:21:32]

LGTM

https://codereview.chromium.org/187133004/diff/20001/runtime/vm/class_table.cc
File runtime/vm/class_table.cc (right):

https://codereview.chromium.org/187133004/diff/20001/runtime/vm/class_table.c...
runtime/vm/class_table.cc:141: // Some of the class table entries maybe NULL as
we create some
maybe -> may be

[Cutch, 2014-03-05 14:41:34]

lgtm

[siva, 2014-03-05 19:24:08]

Committed patchset #2 manually as r33340 (presubmit successful).