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

runtime/vm/stack_frame_test.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 "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
@@ skipping 79 matching lines @@
     if (count == frame_index) {
       // Find the function corresponding to this frame and check if it
       // matches the function name passed in.
       const Function& function =
           Function::Handle(frame->LookupDartFunction());
       if (function.IsNull()) {
         FATAL("StackFrame_validateFrame fails, invalid dart frame.\n");
       }
       const char* name = function.ToFullyQualifiedCString();
       // Currently all unit tests are loaded as being part of dart:core-lib.
-      Isolate* isolate = Isolate::Current();
       String& url = String::Handle(String::New(TestCase::url()));
       const Library& lib = Library::Handle(Library::LookupLibrary(url));
       ASSERT(!lib.IsNull());
       const char* lib_name = String::Handle(lib.url()).ToCString();
       intptr_t length = OS::SNPrint(NULL, 0, "%s_%s", lib_name, expected_name);
-      char* full_name = isolate->current_zone()->Alloc<char>(length + 1);
+      char* full_name = Thread::Current()->zone()->Alloc<char>(length + 1);
       ASSERT(full_name != NULL);
       OS::SNPrint(full_name, (length + 1), "%s_%s", lib_name, expected_name);
       if (strcmp(full_name, name) != 0) {
         FATAL("StackFrame_validateFrame fails, incorrect frame.\n");
       }
       return;
     }
     count += 1;  // Count the dart frames.
     frame = frames.NextFrame();
   }
@@ skipping 204 matching lines @@
       "}";
   }
   Dart_Handle lib = TestCase::LoadTestScript(
       kScriptChars,
       reinterpret_cast<Dart_NativeEntryResolver>(native_lookup));
   Dart_Handle cls = Dart_GetClass(lib, NewString("StackFrame2Test"));
   EXPECT_VALID(Dart_Invoke(cls, NewString("testMain"), 0, NULL));
 }
 
 }  // namespace dart