fixes #150, broken code in js_number.dart

tool/input_sdk/private/js_number.dart

Index: tool/input_sdk/private/js_number.dart
diff --git a/tool/input_sdk/private/js_number.dart b/tool/input_sdk/private/js_number.dart
index 63afa4b29b2dabdb6e67a2024dbfac06efa961d5..1b8a137b85f0c3bf90b3b40d5339da5ca0c24ac2 100644
--- a/tool/input_sdk/private/js_number.dart
+++ b/tool/input_sdk/private/js_number.dart
@@ -166,7 +166,7 @@ class JSNumber extends Interceptor implements num {
       // Then we don't know how to handle it at all.
       throw new UnsupportedError("Unexpected toString result: $result");
     }
-    String result = JS('String', '#', match[1]);
+    result = JS('String', '#', match[1]);
     int exponent = JS("int", "+#", match[3]);
     if (match[2] != null) {
       result = JS('String', '# + #', result, match[2]);