Simplify equality checks and get rid of unreachable code in number and bool.

compiler/lib/implementation/number.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.
 
 class NumberImplementation implements int, double native "Number" {
+
   NumberImplementation operator +(NumberImplementation other) native;
   NumberImplementation operator -(NumberImplementation other) native;
   NumberImplementation operator *(NumberImplementation other) native;
   NumberImplementation operator /(NumberImplementation other) native;
   NumberImplementation operator ~/(NumberImplementation other) native;
   NumberImplementation operator %(NumberImplementation shiftAmount) native;
   NumberImplementation operator negate() native;
+
   int operator |(int other) native;
   int operator &(int other) native;
   int operator ^(int other) native;
   int operator <<(int shiftAmount) native;
   int operator >>(int shiftAmount) native;
   int operator ~() native;
+
   bool operator ==(NumberImplementation other) native;
   bool operator <(NumberImplementation other) native;
   bool operator <=(NumberImplementation other) native;
   bool operator >(NumberImplementation other) native;
   bool operator >=(NumberImplementation other) native;
 
-
   NumberImplementation remainder(num other) native;
   NumberImplementation abs() native;
   NumberImplementation round() native;
   NumberImplementation floor() native;
   NumberImplementation ceil() native;
   NumberImplementation truncate() native;
 
   // CompareTo has to give a complete order, including -0/+0, NaN and
   // Infinities.
   // Order is: -Inf < .. < -0.0 < 0.0 .. < +inf < NaN.
@@ skipping 50 matching lines @@
 
   int hashCode() native;
   get dynamic() { return toDouble(); }
 }
 
 class _NumberJsUtil {
   static void _throwIllegalArgumentException(var argument) native {
     throw new IllegalArgumentException([argument]);
   }
 }