Bug 994876 followup - Fix assert.

js/src/jit/BaselineIC.h

@@ -3555,7 +3555,7 @@ class ICSetElem_DenseAdd : public ICUpdatedStub
         return type_;
     }
     size_t protoChainDepth() const {
-        MOZ_ASSERT(extra_ < MAX_PROTO_CHAIN_DEPTH);
+        MOZ_ASSERT(extra_ <= MAX_PROTO_CHAIN_DEPTH);
         return extra_;
     }