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

runtime/vm/symbols.cc

 // Copyright (c) 2012, 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/symbols.h"
 
 #include "vm/handles.h"
 #include "vm/handles_impl.h"
 #include "vm/hash_table.h"
 #include "vm/isolate.h"
@@ skipping 332 matching lines @@
 }
 
 
 RawString* Symbols::FromUTF8(const uint8_t* utf8_array, intptr_t array_len) {
   if (array_len == 0 || utf8_array == NULL) {
     return FromLatin1(reinterpret_cast<uint8_t*>(NULL), 0);
   }
   Utf8::Type type;
   intptr_t len = Utf8::CodeUnitCount(utf8_array, array_len, &type);
   ASSERT(len != 0);
-  Zone* zone = Isolate::Current()->current_zone();
+  Zone* zone = Thread::Current()->zone();
   if (type == Utf8::kLatin1) {
     uint8_t* characters = zone->Alloc<uint8_t>(len);
     Utf8::DecodeToLatin1(utf8_array, array_len, characters, len);
     return FromLatin1(characters, len);
   }
   ASSERT((type == Utf8::kBMP) || (type == Utf8::kSupplementary));
   uint16_t* characters = zone->Alloc<uint16_t>(len);
   Utf8::DecodeToUTF16(utf8_array, array_len, characters, len);
   return FromUTF16(characters, len);
 }
@@ skipping 93 matching lines @@
 RawObject* Symbols::GetVMSymbol(intptr_t object_id) {
   ASSERT(IsVMSymbolId(object_id));
   intptr_t i = (object_id - kMaxPredefinedObjectIds);
   if ((i > kIllegal) && (i < Symbols::kMaxPredefinedId)) {
     return symbol_handles_[i]->raw();
   }
   return Object::null();
 }
 
 }  // namespace dart