Add Code-related fields to postmortem metadata

Review URL: https://chromiumcodereview.appspot.com/9361008
Patch from David Pacheco <dap@joyent.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10986 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

tools/gen-postmortem-metadata.py

@@ -115,6 +115,9 @@ extras_accessors = [
     'ConsString, second, String, kSecondOffset',
     'ExternalString, resource, Object, kResourceOffset',
     'SeqAsciiString, chars, char, kHeaderSize',
+    'SharedFunctionInfo, code, Code, kCodeOffset',
+    'Code, instruction_start, uintptr_t, kHeaderSize',
+    'Code, instruction_size, int, kInstructionSizeOffset',
 ];
 
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