bisect-kit: fix chrome bisect issues

 1. remove a commit filtering in build_revlist(). It was an
    optimization, which is wrong.
 2. fix sorting in TimeSeriesTree.events(), which should order commits
    only by commit time

BUG=b:123161903,b:123676169,b:126133763,chromium:933178
TEST=run reproduce commands mentioned in above bugs

Change-Id: I348dfab69879c221c6d8fecb28a67171a9ac8e20
Reviewed-on: https://chromium-review.googlesource.com/1486951
Commit-Ready: Kuang-che Wu <kcwu@chromium.org>
Tested-by: Kuang-che Wu <kcwu@chromium.org>
Reviewed-by: Chi-Ngai Wan <cnwan@google.com>
diff --git a/bisect_kit/codechange.py b/bisect_kit/codechange.py
index 1cbd854..5b4a095 100644
--- a/bisect_kit/codechange.py
+++ b/bisect_kit/codechange.py
@@ -840,10 +840,7 @@
       next_float = specs[i + 1]
       logger.debug('[%d], between %s (%s) and %s (%s)', i, prev_float.name,
                    prev_float.timestamp, next_float.name, next_float.timestamp)
-      for action in self.generate_actions_between_specs(prev_float, next_float):
-        if action.timestamp < fixed_specs[0].timestamp:
-          continue
-        actions.append(action)
+      actions += self.generate_actions_between_specs(prev_float, next_float)
     action_groups = self.reorder_actions(actions)
 
     spec = self.synthesize_fixed_spec(float_specs[0], fixed_specs[0].timestamp)