review request (S): 7126041: jdk7u4 b05 and b06 crash with RubyMine 3.2.4, works well with b04

[Roland Westrelin]

> A comment on the is_safepoint function would be helpful.  Otherwise it looks good.

Thanks. I'll add a comment. 
Do you agree with Igor that the function should be a method of Canonicalizer. I think it's fine as a local utility function.

Roland.