Get rid of deprecated methods accessing mutator_thread_ instead of current 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 14 matching lines @@
   virtual int GetId() const { return 3; }
 
  private:
   int* ptr_;
 };
 
 
 class TestStackResource : public StackResource {
  public:
   explicit TestStackResource(int* ptr)
-      : StackResource(Isolate::Current()), ptr_(ptr) {
+      : StackResource(Thread::Current()), ptr_(ptr) {
     EXPECT_EQ(1, *ptr_);
     *ptr_ = 2;
   }
 
   ~TestStackResource() {
     EXPECT_EQ(6, *ptr_);
     *ptr_ = 7;
   }
 
   int value() const { return *ptr_; }
   virtual int GetId() const { return 3; }
 
  private:
   int* ptr_;
 };
 
 
 class TestStackedStackResource : public StackResource {
  public:
   explicit TestStackedStackResource(int* ptr)
-      : StackResource(Isolate::Current()), ptr_(ptr) {
+      : StackResource(Thread::Current()), ptr_(ptr) {
     EXPECT_EQ(3, *ptr_);
     *ptr_ = 4;
   }
 
   ~TestStackedStackResource() {
     EXPECT_EQ(5, *ptr_);
     *ptr_ = 6;
   }
 
   int value() const { return *ptr_; }
@@ skipping 93 matching lines @@
     if (setjmp(*jump.Set()) == 0) {
       StackResourceLongJumpHelper(&data, &jump);
       UNREACHABLE();
     }
     EXPECT_EQ(7, data);
   }
   ASSERT(base == Thread::Current()->long_jump_base());
 }
 
 }  // namespace dart