Switch to CharMatcher.whitespace()

Available in Guava 19.0, this method change eventually allows
avoiding allocation of unused CharMatchers.

Change-Id: Ie1bc2344208223e5805d901ef8afb6588d6122eb

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

diff --git a/gitiles-servlet/src/main/java/com/google/gitiles/DefaultAccess.java b/gitiles-servlet/src/main/java/com/google/gitiles/DefaultAccess.java
index 5fda0df..6fc3211 100644
--- a/gitiles-servlet/src/main/java/com/google/gitiles/DefaultAccess.java
+++ b/gitiles-servlet/src/main/java/com/google/gitiles/DefaultAccess.java
@@ -185,7 +185,7 @@
       File descFile = new File(repo.getDirectory(), "description");
       if (descFile.exists()) {
         desc = new String(IO.readFully(descFile));
-        if (DEFAULT_DESCRIPTION.equals(CharMatcher.WHITESPACE.trimFrom(desc))) {
+        if (DEFAULT_DESCRIPTION.equals(CharMatcher.whitespace().trimFrom(desc))) {
           desc = null;
         }
       } else if (configError != null) {