Bug 1257618 - Kill bogus "level should increase" when charging message r=snorp

The battery level can decrease while we're trying to charge. Most commonly
many devices oscillate between 99% and 100% when fully charged. This situation
could also happen if the device is receiving less power than it's using. Therefore
we shouldn't treat this as an extraordinary situation.

MozReview-Commit-ID: eN3W9P5oty

--HG--
extra : amend_source : abd0231d8514a9bbe9d8ad21ed2de7dba68bbc91

mobile/android/base/java/org/mozilla/gecko/GeckoBatteryManager.java

@@ -128,7 +128,6 @@ public class GeckoBatteryManager extends BroadcastReceiver {
 
                     if (sCharging) {
                         if (dLevel < 0) {
-                            Log.w(LOGTAG, "When charging, level should increase!");
                             sRemainingTime = kUnknownRemainingTime;
                         } else {
                             sRemainingTime = Math.round(dt / dLevel * (1.0 - sLevel));