fix spelling in core libraries

sdk/lib/internal/sort.dart

 // Copyright (c) 2011, 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.
 
 part of dart._internal;
 
 /**
  * Dual-Pivot Quicksort algorithm.
  *
  * This class implements the dual-pivot quicksort algorithm as presented in
@@ skipping 89 matching lines @@
     if (compare(el1, el4) > 0) { var t = el1; el1 = el4; el4 = t; }
     if (compare(el3, el4) > 0) { var t = el3; el3 = el4; el4 = t; }
     if (compare(el2, el5) > 0) { var t = el2; el2 = el5; el5 = t; }
     if (compare(el2, el3) > 0) { var t = el2; el2 = el3; el3 = t; }
     if (compare(el4, el5) > 0) { var t = el4; el4 = el5; el5 = t; }
 
     var pivot1 = el2;
     var pivot2 = el4;
 
     // el2 and el4 have been saved in the pivot variables. They will be written
-    // back, once the partioning is finished.
+    // back, once the partitioning is finished.
     a[index1] = el1;
     a[index3] = el3;
     a[index5] = el5;
 
     a[index2] = a[left];
     a[index4] = a[right];
 
     int less = left + 1;    // First element in the middle partition.
     int great = right - 1;  // Last element in the middle partition.
 
     bool pivots_are_equal = (compare(pivot1, pivot2) == 0);
     if (pivots_are_equal) {
       var pivot = pivot1;
-      // Degenerated case where the partioning becomes a dutch national flag
+      // Degenerated case where the partitioning becomes a dutch national flag
       // problem.
       //
       // [ |  < pivot  | == pivot | unpartitioned | > pivot  | ]
       //  ^             ^          ^             ^            ^
       // left         less         k           great         right
       //
       // a[left] and a[right] are undefined and are filled after the
       // partitioning.
       //
       // Invariants:
@@ skipping 201 matching lines @@
     } else {
       // The second partition looks as follows:
       // [  *  |  >= pivot1 && <= pivot2  | * ]
       //        ^                        ^
       //       less                    great
       // Simply sort it by recursive descent.
       _doSort(a, less, great, compare);
     }
   }
 }