spec-test-script: Disable conversions.wast on i386 (#2269)

tests/wamr-test-suites/spec-test-script/all.py

@@ -73,7 +73,8 @@ def ignore_the_case(
     if not multi_module_flag and case_name in ["imports", "linking"]:
         return True
 
-    if "i386" == target and case_name in ["float_exprs"]:
+    # Note: x87 doesn't preserve sNaN and makes some relevant tests fail.
+    if "i386" == target and case_name in ["float_exprs", "conversions"]:
         return True
 
     if gc_flag: