Added support for improvement_direction to relevant values, which is propogated to chartjson.

tools/telemetry/telemetry/value/failure.py

Index: tools/telemetry/telemetry/value/failure.py
diff --git a/tools/telemetry/telemetry/value/failure.py b/tools/telemetry/telemetry/value/failure.py
index 3b51b61c7d89f914660a4ca4532d2747801519ae..e8078fdbd5f95034676a33533351c2009b42cfbe 100644
--- a/tools/telemetry/telemetry/value/failure.py
+++ b/tools/telemetry/telemetry/value/failure.py
@@ -81,9 +81,10 @@ class FailureValue(value_module.Value):
     kwargs = value_module.Value.GetConstructorKwArgs(value_dict, page_dict)
     del kwargs['name']
     del kwargs['units']
-    important = kwargs.get('important', None)
-    if important != None:
+    if 'important' in kwargs:
       del kwargs['important']
+    if 'higher_is_better' in kwargs:
+      del kwargs['higher_is_better']
     kwargs['exc_info'] = FailureValue._GetExcInfoFromMessage(
         value_dict['value'])