crosperf: allow weight in cwp approximation larger than 1

This patch changed the check on the weight in cwp approximation mode.
The weight should be a float no less than 0.

BUG=chromium:924593
TEST=Tested with a simple experiment on eve.

Change-Id: Ia5ef804b5f11e36f6b5066fba6f40855bd716d2f
Reviewed-on: https://chromium-review.googlesource.com/1431272
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Zhizhou Yang <zhizhouy@google.com>
Reviewed-by: Luis Lozano <llozano@chromium.org>
diff --git a/crosperf/experiment_factory.py b/crosperf/experiment_factory.py
index 20e0fdb..3a1efb8 100644
--- a/crosperf/experiment_factory.py
+++ b/crosperf/experiment_factory.py
@@ -205,8 +205,8 @@
         if run_local:
           raise RuntimeError('run_local must be set to False to use CWP '
                              'approximation')
-        if weight > 1 or weight < 0:
-          raise RuntimeError('Weight should be a float between 0 and 1')
+        if weight < 0:
+          raise RuntimeError('Weight should be a float no less than 0')
       elif cwp_dso:
         raise RuntimeError('With DSO specified, each benchmark should have a '
                            'weight')