Cleanup IntX to implement Comparable<FixNum> which is more descriptive than Comparable as it would …

pkg/fixnum/lib/src/intx.dart

Index: pkg/fixnum/lib/src/intx.dart
diff --git a/pkg/fixnum/lib/src/intx.dart b/pkg/fixnum/lib/src/intx.dart
index 859cb957b60510576ec649087f675796a739cfee..7adbf0c10b3edf3afebd2d0eedf98c3d7b7767ba 100644
--- a/pkg/fixnum/lib/src/intx.dart
+++ b/pkg/fixnum/lib/src/intx.dart
@@ -7,7 +7,7 @@ part of fixnum;
 /**
  * A fixed-precision integer.
  */
-abstract class IntX implements Comparable {
+abstract class IntX implements Comparable<IntX> {
 
   /** Addition operator. */
   IntX operator +(other);
@@ -80,8 +80,6 @@ abstract class IntX implements Comparable {
    */
   IntX shiftRightUnsigned(int shiftAmount);
 
-  int compareTo(Comparable other);
-
   /**
    * Returns `true` if and only if [other] is an int or IntX equal in
    * value to this integer.