Add a `jit-on-first-use` "compiler" option to ART's testrunner script.

This can be used to filter tests in test/knownfailures.json.

Test: art/test/testrunner/testrunner.py --jit-on-first-use
Bug: 62611253
Change-Id: Ie45ee10b794dc9f0749ef8fb0d174cc38653c6ba
diff --git a/test/testrunner/testrunner.py b/test/testrunner/testrunner.py
index 2fa7d2a..b5f4fd3 100755
--- a/test/testrunner/testrunner.py
+++ b/test/testrunner/testrunner.py
@@ -153,8 +153,8 @@
   VARIANT_TYPE_DICT['address_sizes'] = {'64', '32'}
   VARIANT_TYPE_DICT['jvmti'] = {'no-jvmti', 'jvmti-stress', 'redefine-stress', 'trace-stress',
                                 'field-stress', 'step-stress'}
-  VARIANT_TYPE_DICT['compiler'] = {'interp-ac', 'interpreter', 'jit', 'optimizing',
-                                   'regalloc_gc', 'speed-profile'}
+  VARIANT_TYPE_DICT['compiler'] = {'interp-ac', 'interpreter', 'jit', 'jit-on-first-use',
+                                   'optimizing', 'regalloc_gc', 'speed-profile'}
 
   for v_type in VARIANT_TYPE_DICT:
     TOTAL_VARIANTS_SET = TOTAL_VARIANTS_SET.union(VARIANT_TYPE_DICT.get(v_type))
@@ -433,6 +433,8 @@
         options_test += ' --interpreter --verify-soft-fail'
       elif compiler == 'jit':
         options_test += ' --jit'
+      elif compiler == 'jit-on-first-use':
+        options_test += ' --jit --runtime-option -Xjitthreshold:0'
       elif compiler == 'speed-profile':
         options_test += ' --random-profile'