Test result page keeps identifying tests as age 1

If a test has not been viewed, the age will keep being 1.
This is because getFailedSince()/failedSince is lazy loaded.
Without having viewed the CaseResult that method is never
called and the prev.failedSince returns '0' which may or may
not be accurate.
http://jenkins.361315.n4.nabble.com/Problem-with-Age-column-on-Test-Results-tab-td3172208.html
(cherry picked from commit bffca9c)

core/src/main/java/hudson/tasks/junit/CaseResult.java

@@ -373,7 +373,7 @@ public int getFailedSince() {
         if (failedSince==0 && getFailCount()==1) {
             CaseResult prev = getPreviousResult();
             if(prev!=null && !prev.isPassed())
-                this.failedSince = prev.failedSince;
+                this.failedSince = prev.getFailedSince();
             else if (getOwner() != null) {
                 this.failedSince = getOwner().getNumber();
             } else {