Fix no preload available crash

Change-Id: If210b29ce09e7bb7cddc6092601b98b77fa8444e
diff --git a/src/com/android/browser/provider/BrowserProvider2.java b/src/com/android/browser/provider/BrowserProvider2.java
index 919a135..d3fb034 100644
--- a/src/com/android/browser/provider/BrowserProvider2.java
+++ b/src/com/android/browser/provider/BrowserProvider2.java
@@ -478,6 +478,9 @@
         }
 
         private byte[] readRaw(Resources res, int id) throws IOException {
+            if (id == 0) {
+                return null;
+            }
             InputStream is = res.openRawResource(id);
             try {
                 ByteArrayOutputStream bos = new ByteArrayOutputStream();