Bug 1260838 - Assert that ScriptSource's reference count is zero upon destruction; r=jimb a=kwierso

MozReview-Commit-ID: 3TKvYlp2EW1

--HG--
extra : histedit_source : fb8df2d073edcb960f656213695ade72e6862ffa

js/src/jsscript.cpp

@@ -2216,6 +2216,7 @@ ScriptSource::~ScriptSource()
         }
     };
 
+    MOZ_ASSERT(refs == 0);
     MOZ_ASSERT_IF(inCompressedSourceSet, data.is<Compressed>());
 
     DestroyMatcher dm(*this);