Fix small typo

Change-Id: I1c76aadcc6de8cb24dcb3e7c2cee61998b6793f3

dev/core/src/com/google/gwt/dev/DevMode.java

diff --git a/dev/core/src/com/google/gwt/dev/DevMode.java b/dev/core/src/com/google/gwt/dev/DevMode.java
index f83b902..f55e144 100644
--- a/dev/core/src/com/google/gwt/dev/DevMode.java
+++ b/dev/core/src/com/google/gwt/dev/DevMode.java
@@ -635,7 +635,7 @@
       return server.getPort();
     } catch (BindException e) {
       System.err.println("Port " + options.getBindAddress() + ':' + getPort()
-          + " is already is use; you probably still have another session active");
+          + " is already in use; you probably still have another session active");
     } catch (Exception e) {
       System.err.println("Unable to start embedded HTTP server");
       e.printStackTrace();