Add a 'secure' constructor to Random in dart:math returning a cryptographically

sdk/lib/_internal/js_runtime/lib/math_patch.dart

Index: sdk/lib/_internal/js_runtime/lib/math_patch.dart
diff --git a/sdk/lib/_internal/js_runtime/lib/math_patch.dart b/sdk/lib/_internal/js_runtime/lib/math_patch.dart
index 34476f24d8a78c21d3e4f119810c6c1226925a96..2ca6d07125f726114dfd2cc84b5aae7ed205920c 100644
--- a/sdk/lib/_internal/js_runtime/lib/math_patch.dart
+++ b/sdk/lib/_internal/js_runtime/lib/math_patch.dart
@@ -60,6 +60,11 @@ class Random {
   @patch
   factory Random([int seed]) =>
       (seed == null) ? const _JSRandom() : new _Random(seed);
+
+  @patch
+  factory Random.secure() {
+    throw new UnsupportedError("Unsupported secure random generator");

[Lasse Reichstein Nielsen, 2015/10/14 11:08:45]

No need to write "unsupported" in the message too, the error's toString prefixes
the message with "Unsupported operation: ".

[regis, 2015/10/14 20:22:35]

Done.
I used the message you suggested for the VM:
No source of cryptographically secure random numbers available.

+  }
 }
 
 class _JSRandom implements Random {