Fix --strong warnings in pkg/fixnum

pkg/fixnum/lib/src/intx.dart

 // Copyright (c) 2012, 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 fixnum;
 
 /**
  * A fixed-precision integer.
  */
 abstract class IntX implements Comparable<IntX> {
@@ skipping 110 matching lines @@
 
   /** Returns `true` if and only if this integer is zero. */
   bool get isZero;
 
   int get hashCode;
 
   /** Returns the absolute value of this integer. */
   IntX abs();
 
   /** Clamps this integer to be in the range [lowerLimit] - [upperLimit]. */
-  IntX clamp(IntX lowerLimit, IntX upperLimit);
+  IntX clamp(lowerLimit, upperLimit);

[sra1, 2016/03/24 20:50:34]

It would be an improvement if the strong mode warning (located in Int32.clamp
which has no types) told me that the inconsistent type (IntX) came from here.

[Leaf, 2016/03/24 20:52:49]

Acknowledged.

 
   /**
    * Returns the minimum number of bits required to store this integer.
    *
    * The number of bits excludes the sign bit, which gives the natural length
    * for non-negative (unsigned) values.  Negative values are complemented to
    * return the bit position of the first bit that differs from the sign bit.
    *
    * To find the the number of bits needed to store the value as a signed value,
    * add one, i.e. use `x.bitLength + 1`.
@@ skipping 84 matching lines @@
    */
   String toHexString();
 
   /**
    * Returns a string representing the value of this integer in the given radix.
    *
    * [radix] must be an integer in the range 2 .. 16, inclusive.
    */
   String toRadixString(int radix);
 }