Small performance improvement.

h2/src/main/org/h2/store/Data.java

@@ -1014,13 +1014,18 @@ public class Data {
      */
     public void checkCapacity(int plus) {
         if (pos + plus >= data.length) {
+            // a separate method to simplify inlining
+            expand(plus);
+        }
+    }
+
+    private void expand(int plus) {
         byte[] d = Utils.newBytes((data.length + plus) * 2);
         // must copy everything, because pos could be 0 and data may be
         // still required
         System.arraycopy(data, 0, d, 0, data.length);
         data = d;
     }
-    }
 
     /**
      * Fill up the buffer with empty space and an (initially empty) checksum