Declare variables in their own statement

To silence a warning from Checkstyle.

Change-Id: I1357935abcebee20f39af24c9420fafe887bc1fe

gitiles-servlet/src/main/java/com/google/gitiles/DiffServlet.java

diff --git a/gitiles-servlet/src/main/java/com/google/gitiles/DiffServlet.java b/gitiles-servlet/src/main/java/com/google/gitiles/DiffServlet.java
index 8b06e56..27b9852 100644
--- a/gitiles-servlet/src/main/java/com/google/gitiles/DiffServlet.java
+++ b/gitiles-servlet/src/main/java/com/google/gitiles/DiffServlet.java
@@ -64,7 +64,8 @@
 
     try (RevWalk walk = new RevWalk(repo);
         TreeWalk tw = newTreeWalk(walk, view)) {
-      boolean showCommit, isFile;
+      boolean showCommit;
+      boolean isFile;
       AbstractTreeIterator oldTree;
       AbstractTreeIterator newTree;
       try {