Unify Date.fromString and support more Iso 8601.

frog/leg/lib/js_helper.dart

Index: frog/leg/lib/js_helper.dart
diff --git a/frog/leg/lib/js_helper.dart b/frog/leg/lib/js_helper.dart
index 1817c5ad354d622daacaa43be50a6bf39e0bec11..4d27fba2efe9ba9952895d6568416f2e92322e27 100644
--- a/frog/leg/lib/js_helper.dart
+++ b/frog/leg/lib/js_helper.dart
@@ -1129,10 +1129,15 @@ class MathNatives {
     checkNull(str);
     if (str is !String) throw new IllegalArgumentException(str);
     var trimmed = str.trim();
-    if (!JS('bool', @'/^(0[xX])?[+-]?[0-9]+$/.test($0)', trimmed)) {
+    if (!JS('bool', @'/^[+-]?(0[xX])?[0-9]+$/.test($0)', trimmed)) {
       throw new BadNumberFormatException(str);
     }
-    var ret = JS('num', @'parseInt($0, 10)', str);
+    var base = 10;;
+    if ((trimmed.length > 2 && (trimmed[1] == 'x' || trimmed[1] == 'X')) ||
+        (trimmed.length > 3 && (trimmed[2] == 'x' || trimmed[2] == 'X'))) {
+      base = 16;
+    }
+    var ret = JS('num', @'parseInt($0, $1)', trimmed, base);
     if (ret.isNaN()) throw new BadNumberFormatException(str);
     return ret;
   }