Bug 1164898 - A few more fixups to display of confidence warning

* Don't display it if we don't have any runs at all for either original or new
* Some capitalization tweaks

ui/partials/perf/compareconfidence.html

@@ -1,8 +1,9 @@
 <span ng-if="result.confidenceText && result.confidence">
-  {{result.confidence|displayPrecision}} (<abbr title="Result of running t-test on base versus new result distribution: higher values indicate greater confidence that the indicated performance difference is statistically meaningful">{{result.confidenceText}}</abbr>)
-  </span>&nbsp;<span ng-if="result.originalRuns.length < 5 || result.newRuns.length < 5"
-        class="glyphicon glyphicon-warning-sign text-warning"
-        tooltip="6 Base / New runs recommended for increased confidence in comparison"
-        tooltip-placement="left"
-        style="cursor:default">
-</span>
+  {{result.confidence|displayPrecision}} (<abbr title="Result of running t-test on base versus new result distribution: higher values indicate greater confidence that the indicated performance difference is statistically meaningful">{{result.confidenceText}}</abbr>)</span>&nbsp;
+<span ng-if="(result.originalRuns.length &&
+             result.newRuns.length) &&
+             (result.originalRuns.length < 6 || result.newRuns.length < 6)"
+      class="glyphicon glyphicon-warning-sign text-warning"
+      tooltip="6 base / new runs recommended for increased confidence in comparison"
+      tooltip-placement="left"
+      style="cursor:default"/>