Fixed assumption of Symbol table size.
Fixed assumption of Symbol table size.

There is no guarantee that executing some Ruby code will only create one
new Symbol instance. Since we lazily load code with the CodeDB, we could
be executing code at any time in any thread, for instance.

jsyeo/rubinius,jsyeo/rubinius,kachick/rubinius,kachick/rubinius,kachick/rubinius,kachick/rubinius,kachick/rubinius,jsyeo/rubinius,jsyeo/rubinius,kachick/rubinius,jsyeo/rubinius,jsyeo/rubinius,jsyeo/rubinius,kachick/rubinius,kachick/rubinius