[gcalctool/vala] Fix exponential serializer

[Robert Ancell <rancell src gnome org>]

commit 4f98c9f75b32b59e88a545a509683047d0f5d081
Author: Robert Ancell <robert ancell canonical com>
Date:   Sat Oct 13 10:14:07 2012 +1300

    Fix exponential serializer

 src/serializer.vala |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/serializer.vala b/src/serializer.vala
index d24e957..8f9fc91 100644
--- a/src/serializer.vala
+++ b/src/serializer.vala
@@ -435,11 +435,11 @@ public class Serializer : Object
         if (exponent < 0)
         {
             exponent = -exponent;
-            string.append ("â");
+            string.append_unichar ('â');
         }
 
         var super_value = "%d".printf (exponent);
-        for (var i = 0; i < super_digits.length; i++)
+        for (var i = 0; i < super_value.length; i++)
             string.append_unichar (super_digits[super_value[i] - '0']);
     }
 }