[heap] Decouple SpaceIterator from ObjectIterator.

src/heap/heap-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_HEAP_INL_H_
 #define V8_HEAP_HEAP_INL_H_
 
 #include <cmath>
 
 #include "src/base/platform/platform.h"
@@ skipping 128 matching lines @@
     /* never in new space and never on a page that is being compacted.    */  \
     DCHECK(!deserialization_complete() ||                                     \
            RootCanBeWrittenAfterInitialization(k##camel_name##RootIndex));    \
     DCHECK(k##camel_name##RootIndex >= kOldSpaceRoots || !InNewSpace(value)); \
     roots_[k##camel_name##RootIndex] = value;                                 \
   }
 ROOT_LIST(ROOT_ACCESSOR)
 #undef ROOT_ACCESSOR
 
 PagedSpace* Heap::paged_space(int idx) {
-  switch (idx) {
-    case OLD_SPACE:
-      return old_space();
-    case MAP_SPACE:
-      return map_space();
-    case CODE_SPACE:
-      return code_space();
-    case NEW_SPACE:
-    case LO_SPACE:
-      UNREACHABLE();
-  }
-  return NULL;
+  DCHECK_NE(idx, LO_SPACE);
+  DCHECK_NE(idx, NEW_SPACE);
+  return static_cast<PagedSpace*>(space_[idx]);
 }
 
-Space* Heap::space(int idx) {
-  switch (idx) {
-    case NEW_SPACE:
-      return new_space();
-    case LO_SPACE:
-      return lo_space();
-    default:
-      return paged_space(idx);
-  }
-}
+Space* Heap::space(int idx) { return space_[idx]; }
 
 Address* Heap::NewSpaceAllocationTopAddress() {
   return new_space_->allocation_top_address();
 }
 
 Address* Heap::NewSpaceAllocationLimitAddress() {
   return new_space_->allocation_limit_address();
 }
 
 Address* Heap::OldSpaceAllocationTopAddress() {
@@ skipping 696 matching lines @@
 
 void VerifySmisVisitor::VisitPointers(Object** start, Object** end) {
   for (Object** current = start; current < end; current++) {
     CHECK((*current)->IsSmi());
   }
 }
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_INL_H_