Remove GlobalHandles::number_of_weak_handles_ and number_of_global_object_weak_handles_

Remove GlobalHandles::number_of_weak_handles_ and number_of_global_object_weak_handles_

This is a preparation patch for inlining MakeWeak() and Clear().

Given that NumberOfWeakHandles() is used only by CHECK_EQ() in serialized.cc and that NumberOfGlobalObjectWeakHandles is unused, it is wasteful to keep track of number_of_weak_handles_ and number_of_global_object_weak_handles_ at every MakeWeak() and Clear(). Instead, we can count the number at the point where NumberOfWeakHandles() or NumberOfGlobalObjectWeakHandles() is called.

BUG=

Committed: http://code.google.com/p/v8/source/detail?r=13443

[haraken, 2013-01-16 18:16:42]

michael: NumberOfGlobalObjectWeakHandles() is unused. If you want to remove it,
I'd be happy to remove it. Thanks for reviewing!

[Michael Starzinger, 2013-01-21 11:41:53]

LGTM. I'll land this. Let's keep NumberOfGlobalObjectWeakHandles() for now, I
can imagine it being valuable during debugging.