Squashed 'src/leveldb/' changes from 7924331..7d41e6f

7d41e6f Merge upstream LevelDB 1.18
803d692 Release 1.18

git-subtree-dir: src/leveldb
git-subtree-split: 7d41e6f89ff04ce9e6a742932924796f69c6e23d

include/leveldb/iterator.h

@@ -61,7 +61,7 @@ class Iterator {
   // Return the value for the current entry.  The underlying storage for
   // the returned slice is valid only until the next modification of
   // the iterator.
-  // REQUIRES: !AtEnd() && !AtStart()
+  // REQUIRES: Valid()
   virtual Slice value() const = 0;
 
   // If an error has occurred, return it.  Else return an ok status.