Fix single module support when compiling with the Closure Compiler
backend.

Review by: cromwellian@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@10830 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/dev/core/src/com/google/gwt/dev/js/ClosureJsRunner.java b/dev/core/src/com/google/gwt/dev/js/ClosureJsRunner.java
index 23ba2ad..0a16f7a 100644
--- a/dev/core/src/com/google/gwt/dev/js/ClosureJsRunner.java
+++ b/dev/core/src/com/google/gwt/dev/js/ClosureJsRunner.java
@@ -241,7 +241,9 @@
     }
 
     // Then the leftovers fragments:
-    closureModuleSequenceMap[fragments - 1] = module++;
+    if (fragments > 1) {
+      closureModuleSequenceMap[fragments - 1] = module++;
+    }
 
     // Finally, the exclusive fragments.
     // The order of the remaining fragments doesn't matter.