Remove unused private member variables found by clang -Wunused-private-field

src/spaces.h

Index: src/spaces.h
diff --git a/src/spaces.h b/src/spaces.h
index 2e5367aa0ec992eee765a8b4516260c5b8fe7acc..56f629e02f5836ecb7a707ede42d0ae45abfda6e 100644
--- a/src/spaces.h
+++ b/src/spaces.h
@@ -2440,11 +2440,9 @@ class FixedSpace : public PagedSpace {
   FixedSpace(Heap* heap,
              intptr_t max_capacity,
              AllocationSpace id,
-             int object_size_in_bytes,
-             const char* name)
+             int object_size_in_bytes)
       : PagedSpace(heap, max_capacity, id, NOT_EXECUTABLE),
-        object_size_in_bytes_(object_size_in_bytes),
-        name_(name) {
+        object_size_in_bytes_(object_size_in_bytes) {
     page_extra_ = Page::kNonCodeObjectAreaSize % object_size_in_bytes;
   }
 
@@ -2461,9 +2459,6 @@ class FixedSpace : public PagedSpace {
  private:
   // The size of objects in this space.
   int object_size_in_bytes_;
-
-  // The name of this space.
-  const char* name_;
 };
 
 
@@ -2474,7 +2469,7 @@ class MapSpace : public FixedSpace {
  public:
   // Creates a map space object with a maximum capacity.
   MapSpace(Heap* heap, intptr_t max_capacity, AllocationSpace id)
-      : FixedSpace(heap, max_capacity, id, Map::kSize, "map"),
+      : FixedSpace(heap, max_capacity, id, Map::kSize),
         max_map_space_pages_(kMaxMapPageIndex - 1) {
   }
 
@@ -2515,7 +2510,7 @@ class CellSpace : public FixedSpace {
  public:
   // Creates a property cell space object with a maximum capacity.
   CellSpace(Heap* heap, intptr_t max_capacity, AllocationSpace id)
-      : FixedSpace(heap, max_capacity, id, JSGlobalPropertyCell::kSize, "cell")
+      : FixedSpace(heap, max_capacity, id, JSGlobalPropertyCell::kSize)
   {}
 
   virtual int RoundSizeDownToObjectAlignment(int size) {