Reland of "[heap] Parallel newspace evacuation, semispace copy, and compaction \o/"

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index 7c5f0984585a25137a8897ebac358f194579ecf0..b7aad77a8ec57de202d9f55e57748b9f85a3740d 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -2917,9 +2917,7 @@ class CompactionSpaceCollection : public Malloced {
  public:
   explicit CompactionSpaceCollection(Heap* heap)
       : old_space_(heap, OLD_SPACE, Executability::NOT_EXECUTABLE),
-        code_space_(heap, CODE_SPACE, Executability::EXECUTABLE),
-        duration_(0.0),
-        bytes_compacted_(0) {}
+        code_space_(heap, CODE_SPACE, Executability::EXECUTABLE) {}
 
   CompactionSpace* Get(AllocationSpace space) {
     switch (space) {
@@ -2934,21 +2932,9 @@ class CompactionSpaceCollection : public Malloced {
     return nullptr;
   }
 
-  void ReportCompactionProgress(double duration, intptr_t bytes_compacted) {
-    duration_ += duration;
-    bytes_compacted_ += bytes_compacted;
-  }
-
-  double duration() const { return duration_; }
-  intptr_t bytes_compacted() const { return bytes_compacted_; }
-
  private:
   CompactionSpace old_space_;
   CompactionSpace code_space_;
-
-  // Book keeping.
-  double duration_;
-  intptr_t bytes_compacted_;
 };