https://bugs.webkit.org/show_bug.cgi?id=92892

Reviewed by Geoffrey Garen.

In our march to remove ClassInfo from our JSCell object headers, we can switch 
C++ code over to grabbing the ClassInfo from the Structure since it is finally 
safe to do so now that Structure access is safe during finalization/destruction. 
The remaining JIT code changes can be done in a separate patch.

* heap/MarkedBlock.cpp:
(JSC::MarkedBlock::callDestructor): We don't want to clear the Structure any more 
since the Structure should still be valid at this point.
* heap/WeakSetInlines.h:
(JSC::WeakBlock::finalize): Ditto.
* runtime/JSCell.h:
(JSC):
* runtime/Structure.h:
(JSC::JSCell::classInfo): Move JSCell's classInfo() to Structure.h so it can be 
inline. Use a different method of getting the JSCell's Structure based on 
whether we're in GC_VALIDATION mode or not, since always using get() will cause 
infinite recursion in GC_VALIDATION mode.
(JSC):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@124355 268f45cc-cd09-0410-ab3c-d52691b4dbfc