Fix timezone extraction for IE and Opera.

sdk/lib/_internal/lib/js_helper.dart

Index: sdk/lib/_internal/lib/js_helper.dart
diff --git a/sdk/lib/_internal/lib/js_helper.dart b/sdk/lib/_internal/lib/js_helper.dart
index 507e89b59ca1481ef67033c3cb4221bc38bcd52a..7e753ef160c00c8277862e632ea5cf588e36f39b 100644
--- a/sdk/lib/_internal/lib/js_helper.dart
+++ b/sdk/lib/_internal/lib/js_helper.dart
@@ -518,29 +518,37 @@ class Primitives {
   }
 
   static String getTimeZoneName(receiver) {
-    // When calling toString on a Date it will emit the timezone in parenthesis.
+    // Firefox and Chrome emit the timezone in parenthesis.
     // Example: "Wed May 16 2012 21:13:00 GMT+0200 (CEST)".
     // We extract this name using a regexp.
     var d = lazyAsJsDate(receiver);
-    String result = JS('String', r'/\((.*)\)/.exec(#.toString())[1]', d);
-    if (result == null) {
-      // Internet Explorer doesn't put the zone name into parenthesis:
-      // For example: Thu Oct 31 14:07:44 PDT 2013
-      result = JS('String',
-                  // Thu followed by a space.
-                  r'/^[A-Z,a-z]{3}\s'
-                  // Oct 31 followed by space.
-                  r'[A-Z,a-z]{3}\s\d+\s'
-                  // Time followed by a space.
-                  r'\d{2}:\d{2}:\d{2}\s'
-                  // The time zone name followed by a space.
-                  r'([A-Z]{3,5})\s'
-                  // The year.
-                  r'\d{4}$/'
-                  '.exec(#.toString())[1]',
-                  d);
-    }
-    return result;
+    List match = JS('JSArray|Null', r'/\((.*)\)/.exec(#.toString())', d);
+    if (match != null) return match[1];
+
+    // Internet Explorer 10+ emits the zone name without parenthesis:
+    // Example: Thu Oct 31 14:07:44 PDT 2013
+    match = JS('JSArray|Null',
+                // Thu followed by a space.
+                r'/^[A-Z,a-z]{3}\s'
+                // Oct 31 followed by space.
+                r'[A-Z,a-z]{3}\s\d+\s'
+                // Time followed by a space.
+                r'\d{2}:\d{2}:\d{2}\s'
+                // The time zone name followed by a space.
+                r'([A-Z]{3,5})\s'
+                // The year.
+                r'\d{4}$/'
+                '.exec(#.toString())',
+                d);
+    if (match != null) return match[1];
+
+    // IE 9 and Opera don't provide the zone name. We fall back to emitting the
+    // UTC/GMT offset.
+    // Example (IE9): Wed Nov 20 09:51:00 UTC+0100 2013
+    //       (Opera): Wed Nov 20 2013 11:03:38 GMT+0100
+    match = JS('JSArray|Null', r'/(?:GMT|UTC)[+-]\d{4}/.exec(#.toString())', d);
+    if (match != null) return match[0];
+    return "";
   }
 
   static int getTimeZoneOffsetInMinutes(receiver) {