6625725: (coll) modCount should not be volatile

Reviewed-by: dholmes

src/share/classes/java/util/HashMap.java

@@ -173,7 +173,7 @@ public class HashMap<K,V>
      * rehash).  This field is used to make iterators on Collection-views of
      * the HashMap fail-fast.  (See ConcurrentModificationException).
      */
-    transient volatile int modCount;
+    transient int modCount;
 
     /**
      * Constructs an empty <tt>HashMap</tt> with the specified initial

src/share/classes/java/util/IdentityHashMap.java

@@ -173,7 +173,7 @@ public class IdentityHashMap<K,V>
     /**
      * The number of modifications, to support fast-fail iterators
      */
-    private transient volatile int modCount;
+    private transient int modCount;
 
     /**
      * The next size value at which to resize (capacity * load factor).

src/share/classes/java/util/WeakHashMap.java

@@ -182,7 +182,7 @@ public class WeakHashMap<K,V>
      *
      * @see ConcurrentModificationException
      */
-    volatile int modCount;
+    int modCount;
 
     @SuppressWarnings("unchecked")
     private Entry<K,V>[] newTable(int n) {