Fix deprecation message

lib/runtime/dart/math.js

Index: lib/runtime/dart/math.js
diff --git a/lib/runtime/dart/math.js b/lib/runtime/dart/math.js
index 948ca4d4ea565666ad0b5005aab1542730074d70..782599615ddf2f96011ff3245ded43534bd5a403 100644
--- a/lib/runtime/dart/math.js
+++ b/lib/runtime/dart/math.js
@@ -43,7 +43,7 @@ dart_library.library('dart/math', null, /* Imports */[
         return `Point(${this.x}, ${this.y})`;
       }
       ['=='](other) {
-        if (!dart.is(other, Point$())) return false;
+        if (!dart.is(other, Point$(core.num))) return false;

[Jennifer Messerly, 2016/03/08 00:21:31]

Hmm, so we now convert `other is Point` to `other is Point<num>`. I think that
should be fine, because you can't create a `Point<dynamic>`. But it's a bit
interesting :)

         return dart.equals(this.x, dart.dload(other, 'x')) && dart.equals(this.y, dart.dload(other, 'y'));
       }
       get hashCode() {