- Reduce the number of Isolate::Current() calls.

runtime/vm/allocation.h

Index: runtime/vm/allocation.h
===================================================================
--- runtime/vm/allocation.h	(revision 36483)
+++ runtime/vm/allocation.h	(working copy)
@@ -96,6 +96,10 @@
   // Implicitly allocate the object in the current zone.
   void* operator new(uword size);
 
+  // Implicitly allocate the object in the current zone given the current
+  // isolate.
+  void* operator new(uword size, BaseIsolate* isolate);
+
   // Ideally, the delete operator should be protected instead of
   // public, but unfortunately the compiler sometimes synthesizes
   // (unused) destructors for classes derived from ZoneObject, which