Revert "Revert "Reinstate type checks in Math.min and Math.max""

sdk/lib/math/math.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.
 
 /**
  * Mathematical constants and functions, plus a random number generator.
  */
 library dart.math;
 
 part "random.dart";
@@ skipping 43 matching lines @@
 /**
   * Returns the lesser of two numbers.
   *
   * Returns NaN if either argument is NaN.
   * The lesser of [:-0.0:] and [:0.0:] is [:-0.0:].
   * If the arguments are otherwise equal (including int and doubles with the
   * same mathematical value) then it is unspecified which of the two arguments
   * is returned.
   */
 num min(num a, num b) {
+  // These partially redundant type checks improve code quality for dart2js.
+  // Most of the improvement is at call sites from the inferred non-null num
+  // return type.
+  if (a is! num) throw new ArgumentError(a);
+  if (b is! num) throw new ArgumentError(b);
+
   if (a > b) return b;
   if (a < b) return a;
   if (b is double) {
     // Special case for NaN and -0.0. If one argument is NaN return NaN.
     // [min] must also distinguish between -0.0 and 0.0.
     if (a is double) {
       if (a == 0.0) {
         // a is either 0.0 or -0.0. b is either 0.0, -0.0 or NaN.
         // The following returns -0.0 if either a or b is -0.0, and it
         // returns NaN if b is NaN.
         return (a + b) * a * b;
       }
     }
     // Check for NaN and b == -0.0.
     if (a == 0 && b.isNegative || b.isNaN) return b;
     return a;
   }
   return a;
 }
 
 /**
   * Returns the larger of two numbers.
   *
   * Returns NaN if either argument is NaN.
   * The larger of [:-0.0:] and [:0.0:] is [:0.0:]. If the arguments are
   * otherwise equal (including int and doubles with the same mathematical value)
   * then it is unspecified which of the two arguments is returned.
   */
 num max(num a, num b) {
+  // These partially redundant type checks improve code quality for dart2js.
+  // Most of the improvement is at call sites from the inferred non-null num
+  // return type.
+  if (a is! num) throw new ArgumentError(a);
+  if (b is! num) throw new ArgumentError(b);
+
   if (a > b) return a;
   if (a < b) return b;
   if (b is double) {
     // Special case for NaN and -0.0. If one argument is NaN return NaN.
     // [max] must also distinguish between -0.0 and 0.0.
     if (a is double) {
       if (a == 0.0) {
         // a is either 0.0 or -0.0. b is either 0.0, -0.0, or NaN.
         // The following returns 0.0 if either a or b is 0.0, and it
         // returns NaN if b is NaN.
@@ skipping 126 matching lines @@
  * Returns NaN if [x] is NaN.
  */
 external double exp(num x);
 
 /**
  * Converts [x] to a double and returns the natural logarithm of the value.
  * Returns negative infinity if [x] is equal to zero.
  * Returns NaN if [x] is NaN or less than zero.
  */
 external double log(num x);