Bug 1414401 - Schedule Wd tests on linux32 r=jgraham

MozReview-Commit-ID: FRpg35u0NWK

--HG--
extra : rebase_source : af0c35be289bff1c1fb4792d678dea307834cc86

taskcluster/ci/test/test-sets.yml

@@ -300,6 +300,7 @@ linux32-tests:
     - reftest-no-accel
     - web-platform-tests
     - web-platform-tests-reftests
+    - web-platform-tests-wdspec
     - xpcshell
 
 linux32-opt-tests: