[test] Key variant flags by variant name everywhere.

test/benchmarks/testcfg.py

Index: test/benchmarks/testcfg.py
diff --git a/test/benchmarks/testcfg.py b/test/benchmarks/testcfg.py
index 2a65037754e862369ff537cbcc41c94876ccf321..0c3698bd601d3ffa1f972f040d7cf5ddfa0b05f2 100644
--- a/test/benchmarks/testcfg.py
+++ b/test/benchmarks/testcfg.py
@@ -31,10 +31,25 @@ import shutil
 import subprocess
 import tarfile
 
+from testrunner.local import statusfile
 from testrunner.local import testsuite
 from testrunner.objects import testcase
 
 
+class BenchmarksVariantGenerator(testsuite.VariantGenerator):
+  # Both --nocrankshaft and --stressopt are very slow. Add TF but without
+  # always opt to match the way the benchmarks are run for performance
+  # testing.
+  def FilterVariantsByTest(self, testcase):
+    if testcase.outcomes and statusfile.OnlyStandardVariant(
+        testcase.outcomes):
+      return self.standard_variant
+    return self.fast_variants
+
+  def GetFlagSets(self, testcase, variant):
+    return testsuite.FAST_VARIANT_FLAGS[variant]
+
+
 class BenchmarksTestSuite(testsuite.TestSuite):
 
   def __init__(self, name, root):
@@ -182,11 +197,8 @@ class BenchmarksTestSuite(testsuite.TestSuite):
 
     os.chdir(old_cwd)
 
-  def VariantFlags(self, testcase, default_flags):
-    # Both --nocrankshaft and --stressopt are very slow. Add TF but without
-    # always opt to match the way the benchmarks are run for performance
-    # testing.
-    return [[], ["--turbo"]]
+  def _VariantGeneratorFactory(self):
+    return BenchmarksVariantGenerator
 
 
 def GetSuite(name, root):