Revert "spidermonkey: Disable tests on ARM"

This reverts commit f9654a8.

At least for now, the problem has gone away on ARMv7 by the switch of
FPU flags used by GCC.

Some details of the bug at:
#16850 (comment)

pkgs/development/interpreters/spidermonkey/17.0.nix

@@ -42,7 +42,7 @@ stdenv.mkDerivation rec {
 
   enableParallelBuilding = true;
 
-  doCheck = !stdenv.isArm; # fails on v7 with "Alignment trap: not handling instruction" in kernel log
+  doCheck = true;
   preCheck = ''
     rm jit-test/tests/sunspider/check-date-format-tofte.js    # https://bugzil.la/600522