Eliminate use of ZONE macro in BitVector class and pass a zone explicitly.

src/lithium-allocator.h

Index: src/lithium-allocator.h
===================================================================
--- src/lithium-allocator.h	(revision 10788)
+++ src/lithium-allocator.h	(working copy)
@@ -424,7 +424,7 @@
     if (InBitsRange(value)) return;
     int new_length = bits_ == NULL ? kInitialLength : bits_->length();
     while (new_length <= value) new_length *= 2;
-    BitVector* new_bits = new(zone) BitVector(new_length);
+    BitVector* new_bits = new(zone) BitVector(new_length, zone);
     if (bits_ != NULL) new_bits->CopyFrom(*bits_);
     bits_ = new_bits;
   }