Fix typo.

runtime/vm/class_table.h

 // Copyright (c) 2012, 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 VM_CLASS_TABLE_H_
 #define VM_CLASS_TABLE_H_
 
 #include "platform/assert.h"
 #include "vm/bitfield.h"
 #include "vm/globals.h"
@@ skipping 137 matching lines @@
   // access, without support for stats data.
   explicit ClassTable(ClassTable* original);
   ~ClassTable();
 
   // Thread-safe.
   RawClass* At(intptr_t index) const {
     ASSERT(IsValidIndex(index));
     return table_[index];
   }
 
-  intptr_t IsValidIndex(intptr_t index) const {
+  bool IsValidIndex(intptr_t index) const {
     return (index > 0) && (index < top_);
   }
 
   bool HasValidClassAt(intptr_t index) const {
     ASSERT(IsValidIndex(index));
     return table_[index] != NULL;
   }
 
   intptr_t NumCids() const { return top_; }
 
@@ skipping 75 matching lines @@
   ClassHeapStats* PreliminaryStatsAt(intptr_t cid);
   void UpdateLiveOld(intptr_t cid, intptr_t size);
   void UpdateLiveNew(intptr_t cid, intptr_t size);
 
   DISALLOW_COPY_AND_ASSIGN(ClassTable);
 };
 
 }  // namespace dart
 
 #endif  // VM_CLASS_TABLE_H_