Use words please.

runtime/observatory/lib/dominator_tree.dart

 // Copyright (c) 2014, 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.
 
 library dominator_tree;
 
 // Flowgraph dominators in O(m log n) time. Implements the algorithm from
 // [Lengauer & Tarjan 1979]
 // T. Lengauer and R.E. Tarjan,
 // "A fast algorithm for finding dominators in a flowgraph",
@@ skipping 67 matching lines @@
       return v;
     } else {
       _compress(v);
       return v.label;
     }
   }
 
   void _link(_Vertex v, _Vertex w) {
     w.ancestor = v;
   }
-  
+
   void computeDominatorTree(Object root) {
     _Vertex r = _asVertex(root);
     int n = _idToVertex.length;
     _dfs(r);
     if (_vertex.length != n) {
       throw new StateError("Not a flowgraph: "
           "only ${_vertex.length} of $n vertices reachable");
     }
     for (int i = n - 1; i >= 1; --i) {
       _Vertex w = _vertex[i];
@@ skipping 13 matching lines @@
     }
     for (int i = 1; i < n; ++i) {
       _Vertex w = _vertex[i];
       if (w.dom != _vertex[w.semi]) {
         w.dom = w.dom.dom;
       }
     }
     r.dom = null;
   }
 }