chore: support nodejs v4

Author: antongolub

Diff for: lib/util/variable.js

@@ -62,8 +62,8 @@ function variablesInScope(context, node) {
  * @param {string} name The name of the variable to search.
  * @returns {ASTNode|null} Return null if the variable could not be found, ASTNode otherwise.
  */
-function findVariableByName(context, node, name = node.name) {
-  const variable = getVariable(variablesInScope(context, node), name);
+function findVariableByName(context, node, name) {
+  const variable = getVariable(variablesInScope(context, node), name || node.name);
 
   if (!variable || !variable.defs[0] || !variable.defs[0].node) {
     return null;