Moves the top_ and end_ words of the Scavenger into mutator thread.

runtime/vm/thread.h

 // Copyright (c) 2015, 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.
 
 #ifndef RUNTIME_VM_THREAD_H_
 #define RUNTIME_VM_THREAD_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/atomic.h"
@@ skipping 347 matching lines @@
   StackResource* top_resource() const { return top_resource_; }
   void set_top_resource(StackResource* value) { top_resource_ = value; }
   static intptr_t top_resource_offset() {
     return OFFSET_OF(Thread, top_resource_);
   }
 
   // Heap of the isolate that this thread is operating on.
   Heap* heap() const { return heap_; }
   static intptr_t heap_offset() { return OFFSET_OF(Thread, heap_); }
 
+  void set_top(uword value) {
+    ASSERT(heap_ != NULL);
+    top_ = value;
+  }
+  void set_end(uword value) {
+    ASSERT(heap_ != NULL);
+    end_ = value;
+  }
+
+  uword top() { return top_; }
+  uword end() { return end_; }
+
+  static intptr_t top_offset() { return OFFSET_OF(Thread, top_); }
+  static intptr_t end_offset() { return OFFSET_OF(Thread, end_); }
+
   int32_t no_handle_scope_depth() const {
 #if defined(DEBUG)
     return no_handle_scope_depth_;
 #else
     return 0;
 #endif
   }
 
   void IncrementNoHandleScopeDepth() {
 #if defined(DEBUG)
@@ skipping 310 matching lines @@
   // Accessed from generated code.
   // ** This block of fields must come first! **
   // For AOT cross-compilation, we rely on these members having the same offsets
   // in SIMARM(IA32) and ARM, and the same offsets in SIMARM64(X64) and ARM64.
   // We use only word-sized fields to avoid differences in struct packing on the
   // different architectures. See also CheckOffsets in dart.cc.
   uword stack_limit_;
   uword stack_overflow_flags_;
   Isolate* isolate_;
   Heap* heap_;
+  uword top_;
+  uword end_;
   uword top_exit_frame_info_;
   StoreBufferBlock* store_buffer_block_;
   uword vm_tag_;
   TaskKind task_kind_;
   RawStackTrace* async_stack_trace_;
 // State that is cached in the TLS for fast access in generated code.
 #define DECLARE_MEMBERS(type_name, member_name, expr, default_init_value)      \
   type_name member_name;
   CACHED_CONSTANTS_LIST(DECLARE_MEMBERS)
 #undef DECLARE_MEMBERS
@@ skipping 107 matching lines @@
 // Disable thread interrupts.
 class DisableThreadInterruptsScope : public StackResource {
  public:
   explicit DisableThreadInterruptsScope(Thread* thread);
   ~DisableThreadInterruptsScope();
 };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_THREAD_H_