[foozzie] Add Liftoff testing

This adds 5% testing of 'ignition' vs 'liftoff', which tests Turbofan vs
Liftoff for wasm code, and tests Ignition vs Turbofan for javascript
code.
It also adds 3% testing of 'liftoff' (x64) vs 'liftoff' (ia32), which
does standard x64 vs ia32 testing for javascript code.

R=machenbach@chromium.org

Bug: chromium:824098, v8:6600
Change-Id: I6a6afae0300efc33f3535541a11695a7bb32dcc5
Reviewed-on: https://chromium-review.googlesource.com/973161
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52111}

tools/clusterfuzz/v8_foozzie.py

@@ -56,6 +56,10 @@ CONFIGS = dict(
     '--no-lazy-inner-functions',
     '--suppress-asm-messages',
   ],
+  liftoff=[
+    '--liftoff',
+    '--suppress-asm-messages',
+  ],
   slow_path=[
     '--force-slow-path',
     '--suppress-asm-messages',

tools/clusterfuzz/v8_foozzie_test.py

@@ -39,7 +39,7 @@ class ConfigTest(unittest.TestCase):
     self.assertEqual(
         [
           '--first-config=ignition',
-          '--second-config=ignition_turbo',
+          '--second-config=ignition_turbo_opt',
           '--second-d8=d8',
         ],
         v8_fuzz_config.Config('foo', Rng()).choose_foozzie_flags(),

tools/clusterfuzz/v8_fuzz_config.py

@@ -13,13 +13,15 @@ FOOZZIE_EXPERIMENTS = [
   [5, 'ignition', 'trusted_opt', 'd8'],
   [10, 'ignition', 'slow_path', 'd8'],
   [5, 'ignition', 'slow_path_opt', 'd8'],
-  [25, 'ignition', 'ignition_turbo', 'd8'],
+  [20, 'ignition', 'ignition_turbo', 'd8'],
   [20, 'ignition', 'ignition_turbo_opt', 'd8'],
-  [5, 'ignition_turbo_opt', 'ignition_turbo_opt', 'clang_x86/d8'],
-  [5, 'ignition_turbo', 'ignition_turbo', 'clang_x86/d8'],
-  [5, 'ignition', 'ignition', 'clang_x86/d8'],
+  [4, 'ignition_turbo_opt', 'ignition_turbo_opt', 'clang_x86/d8'],
+  [4, 'ignition_turbo', 'ignition_turbo', 'clang_x86/d8'],
+  [4, 'ignition', 'ignition', 'clang_x86/d8'],
   [5, 'ignition', 'ignition', 'clang_x64_v8_arm64/d8'],
   [5, 'ignition', 'ignition', 'clang_x86_v8_arm/d8'],
+  [5, 'ignition', 'liftoff', 'd8'],
+  [3, 'liftoff', 'liftoff', 'clang_x86/d8'],
 ]
 
 class Config(object):