[Telemetry] Remove internal dependencies on BuildbotOutputFormatter

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 cd614e70f9712243053ec459008c6c77ed6bed95..027672d156a3b853e1d6940abe20ff96bd43080e 100644
--- a/tools/telemetry/telemetry/value/failure.py
+++ b/tools/telemetry/telemetry/value/failure.py
@@ -43,7 +43,7 @@ class FailureValue(value_module.Value):
 
   def __repr__(self):
     if self.page:
-      page_name = self.page.url
+      page_name = self.page.name

[nednguyen, 2015/06/05 14:58:08]

This seems right eventually, but would it mess up the dashboard's data?
What is the default value of page.name?

[eakuefner, 2015/06/05 15:03:57]

No, this won't interfere with the dashboard since the chart JSON pipeline makes
no direct use of __repr__. Stringification is only used by tests and
serialization, and ChartJsonOutputFormatter uses additional machinery originally
introduced by BuildbotOutputFormatter to make sure that pages without names are
referred to by URL instead, in chart JSON in particular.

As it stands, this is fixing a stringification bug where Telemetry will crash if
it tries to serialize a non-Page Story, as in story_runner_unittest.

     else:
       page_name = None
     return 'FailureValue(%s, %s)' % (