code: private static int estimateCallCost(Node fnNode, boolean referencesThis) {
      Node argsNode = NodeUtil.getFunctionParameters(fnNode);
      int numArgs = argsNode.getChildCount();
  
      int callCost = NAME_COST_ESTIMATE + PAREN_COST;
      if (numArgs > 0) {
        callCost += (numArgs * NAME_COST_ESTIMATE) + ((numArgs - 1) * COMMA_COST);
      }
  
      if (referencesThis) {
        // TODO(johnlenz): Update this if we start supporting inlining
        // other functions that reference this.
        // The only functions that reference this that are currently inlined
        // are those that are called via ".call" with an explicit "this".
        callCost += 5 + 5;  // ".call" + "this,"
      }
  
      return callCost;
    }
docs: Gets an estimate of the cost in characters of making the function call:
  the sum of the identifiers and the separators.
  @param referencesThis