Add wasm_no_native variant

This new variant is executed on a small number of bots as part of the
"extra" suite. It checks that the wasm-jit-to-native flag can still be
disabled if unexpected failures pop up on a release branch.

R=machenbach@chromium.org

Bug: v8:7417
Change-Id: I1658cb2f04302fa80915b59bfedd85d980742db5
Reviewed-on: https://chromium-review.googlesource.com/909213Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51204}

tools/testrunner/local/variants.py

@@ -22,7 +22,8 @@ ALL_VARIANT_FLAGS = {
   # Trigger stress sampling allocation profiler with sample interval = 2^14
   "stress_sampling": [["--stress-sampling-allocation-profiler=16384"]],
   "trusted": [["--no-untrusted-code-mitigations"]],
-  "wasm_traps": [["--wasm_trap_handler", "--invoke-weak-callbacks", "--wasm-jit-to-native"]],
+  "wasm_traps": [["--wasm-trap-handler", "--invoke-weak-callbacks"]],
+  "wasm_no_native": [["--no-wasm-jit-to-native"]],
 }
 
 SLOW_VARIANTS = set([

tools/testrunner/standard_runner.py

@@ -44,7 +44,7 @@ VARIANT_ALIASES = {
   # Shortcut for the two above ("more" first - it has the longer running tests).
   "exhaustive": MORE_VARIANTS + VARIANTS,
   # Additional variants, run on a subset of bots.
-  "extra": ["future", "liftoff", "trusted"],
+  "extra": ["future", "liftoff", "trusted", "wasm_no_native"],
 }
 
 GC_STRESS_FLAGS = ["--gc-interval=500", "--stress-compaction",