Migrate most uses of Isolate::current_zone to Thread::zone.

runtime/vm/locations.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/locations.h"
 
 #include "vm/assembler.h"
 #include "vm/il_printer.h"
 #include "vm/intermediate_language.h"
 #include "vm/flow_graph_compiler.h"
@@ skipping 201 matching lines @@
   } else {
     f->Print("%s", Name());
   }
 }
 
 
 const char* Location::ToCString() const {
   char buffer[1024];
   BufferFormatter bf(buffer, 1024);
   PrintTo(&bf);
-  return Isolate::Current()->current_zone()->MakeCopyOfString(buffer);
+  return Thread::Current()->zone()->MakeCopyOfString(buffer);
 }
 
 
 void Location::Print() const {
   if (kind() == kStackSlot) {
     ISL_Print("S%+" Pd "", stack_index());
   } else {
     ISL_Print("%s", Name());
   }
 }
@@ skipping 116 matching lines @@
       // with the right representation because register allocator does not know
       // how they are used within the instruction template.
       ASSERT(in(i).IsMachineRegister());
       ASSERT(live_registers()->Contains(in(i)));
     }
   }
 }
 #endif
 
 }  // namespace dart