Introduce a 'baseline' variant for the compiler.

Implemented as a stripped down version of the optimizing compiler,
not running any optimization.

Adjust code to still work with expectations in code generators.

bug: 111397239

Test: test.py --baseline
Change-Id: I4328283825f9a890616e7496ed4c1e77d6bcc5dd
diff --git a/test/knownfailures.json b/test/knownfailures.json
index 002ad07..e27a4d6 100644
--- a/test/knownfailures.json
+++ b/test/knownfailures.json
@@ -946,6 +946,7 @@
           "676-proxy-jit-at-first-use",
           "676-resolve-field-type",
           "685-deoptimizeable",
+          "685-shifts",
           "706-checker-scheduler",
           "707-checker-invalid-profile",
           "714-invoke-custom-lambda-metafactory",
@@ -1093,5 +1094,10 @@
         "env_vars": {"SANITIZE_HOST": "address"},
         "bug": "b/112993554",
         "description": ["Timeout with ASan and interp-ac on 32-bit host (x86)."]
+    },
+    {
+        "tests": ["454-get-vreg", "457-regs"],
+        "variant": "baseline",
+        "description": ["Tests are expected to fail with baseline."]
     }
 ]