Fix compile warning [-Wtype-limits]

src/heap/heap.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_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 937 matching lines @@
   // Checks whether an address/object in the heap (including auxiliary
   // area and unused area).
   bool Contains(Address addr);
   bool Contains(HeapObject* value);
 
   // Checks whether an address/object in a space.
   // Currently used by tests, serialization and heap verification only.
   bool InSpace(Address addr, AllocationSpace space);
   bool InSpace(HeapObject* value, AllocationSpace space);
 
+  // Checks whether the space is valid.
+  static bool IsValidAllocationSpace(AllocationSpace space);
+
   // Checks whether the given object is allowed to be migrated from it's
   // current space into the given destination space. Used for debugging.
   inline bool AllowedToBeMigrated(HeapObject* object, AllocationSpace dest);
 
   // Sets the stub_cache_ (only used when expanding the dictionary).
   void public_set_code_stubs(UnseededNumberDictionary* value) {
     roots_[kCodeStubsRootIndex] = value;
   }
 
   // Support for computing object sizes for old objects during GCs. Returns
@@ skipping 1759 matching lines @@
   DisallowHeapAllocation no_allocation;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_HEAP_H_