Stop using unittest in point_test and rectangle_test.

pkg/dev_compiler/tool/input_sdk/lib/math/rectangle.dart

 // Copyright (c) 2013, 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.math;
 
 /**
  * A base class for representing two-dimensional axis-aligned rectangles.
  *
  * This rectangle uses a left-handed Cartesian coordinate system, with x
  * directed to the right and y directed down, as per the convention in 2D
@@ skipping 22 matching lines @@
   T get right => left + width;
   /** The y-coordinate of the bottom edge. */
   T get bottom => top + height;
 
   String toString() {
     return 'Rectangle ($left, $top) $width x $height';
   }
 
   bool operator ==(other) {
     if (other is !Rectangle) return false;
-    return left == other.left && top == other.top && right == other.right &&
-        bottom == other.bottom;
+    // TODO(rnystrom): Type promotion doesn't currently promote the [other]
+    // to Rectangle from the above line, so do it explicitly here to avoid a
+    // dynamic send and work around:
+    // https://github.com/dart-lang/sdk/issues/27551
+    var otherRect = other as Rectangle;
+    return left == otherRect.left &&
+        top == otherRect.top &&
+        right == otherRect.right &&
+        bottom == otherRect.bottom;
   }
 
   int get hashCode => _JenkinsSmiHash.hash4(left.hashCode, top.hashCode,
       right.hashCode, bottom.hashCode);
 
   /**
    * Computes the intersection of `this` and [other].
    *
    * The intersection of two axis-aligned rectangles, if any, is always another
    * axis-aligned rectangle.
@@ skipping 212 matching lines @@
 
 /**
  * Converts a negative [int] or [double] to a zero-value of the same type.
  *
  * Returns `0` if value is int, `0.0` if value is double.
  */
 num/*=T*/ _clampToZero/*<T extends num>*/(num/*=T*/ value) {
   assert(value < 0);
   return -value * 0;
 }