Fix comments

lib/src/graph.dart

 // Copyright (c) 2015, 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.
 
 /// A library to work with graphs. It contains a couple algorithms, including
 /// Tarjan's algorithm to compute strongest connected components in a graph and
 /// Cooper et al's dominator algorithm.
 ///
 /// Portions of the code in this library was adapted from
 /// `package:analyzer/src/generated/collection_utilities.dart`.
@@ skipping 36 matching lines @@
     helper(n) {
       if (!seen.add(n)) return;
       targetsOf(n).forEach(helper);
       result.add(n);
     }
     helper(root);
     return result;
   }
 
   /// Return a list of nodes that form a cycle containing the given node. If the
-  /// node is not part of this graph, then a list containing only the node
-  /// itself will be returned.
+  /// node is not part of a cycle in this graph, then a list containing only the
+  /// node itself will be returned.
   List<N> findCycleContaining(N node) {
     assert(node != null);
     _SccFinder<N> finder = new _SccFinder<N>(this);
     return finder._componentContaining(node);
   }
 
+  /// Returns a dominator tree starting from root. This is a new graph, with the
+  /// same nodes as this graph, but where edges exist between a node and the
+  /// nodes it immediately dominates. For example, this graph:
+  ///
+  ///       root
+  ///       /   \
+  ///      a     b
+  ///      |    / \
+  ///      c   d   e
+  ///       \ / \ /
+  ///        f   g
+  ///
+  /// Produces this tree:
+  ///
+  ///       root
+  ///       /|  \
+  ///      a |   b
+  ///      | |  /|\
+  ///      c | d | e
+  ///        |   |
+  ///        f   g
+  ///
+  /// Internally we compute dominators using (Cooper, Harvey, and Kennedy's
+  /// algorithm)[http://www.cs.rice.edu/~keith/EMBED/dom.pdf].
   Graph<N> dominatorTree(N root) {
     var iDom = (new _DominatorFinder(this)..run(root)).immediateDominators;
     var graph = new EdgeListGraph<N>();
     for (N node in iDom.keys) {
       if (node != root) graph.addEdge(iDom[node], node);
     }
     return graph;
   }
 }
 
@@ skipping 208 matching lines @@
       while (postOrderId[finger1] < postOrderId[finger2]) {
         finger1 = immediateDominators[finger1];
       }
       while (postOrderId[finger2] < postOrderId[finger1]) {
         finger2 = immediateDominators[finger2];
       }
     }
     return finger1;
   }
 }