Migrate LongJumpScope to Thread.

runtime/vm/allocation_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 "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/longjump.h"
 #include "vm/unit_test.h"
 
 namespace dart {
@@ skipping 135 matching lines @@
 static void StackResourceLongJumpHelper(int* ptr, LongJumpScope* jump) {
   TestStackResource stacked(ptr);
   EXPECT_EQ(2, *ptr);
   *ptr = 3;
   StackedStackResourceLongJumpHelper(ptr, jump);
   UNREACHABLE();
 }
 
 
 TEST_CASE(StackResourceLongJump) {
-  LongJumpScope* base = Isolate::Current()->long_jump_base();
+  LongJumpScope* base = Thread::Current()->long_jump_base();
   {
     LongJumpScope jump;
     int data = 1;
     if (setjmp(*jump.Set()) == 0) {
       StackResourceLongJumpHelper(&data, &jump);
       UNREACHABLE();
     }
     EXPECT_EQ(7, data);
   }
-  ASSERT(base == Isolate::Current()->long_jump_base());
+  ASSERT(base == Thread::Current()->long_jump_base());
 }
 
 }  // namespace dart