fix: Restore compatibility with IE11

Author: prantlf

lib/formatter.js

@@ -24,8 +24,8 @@
     var i = 0
     var length = 0
     var indentString = indent !== undefined
-                         ? typeof indent === 'number'
-                           ? ' '.repeat(indent) : indent : '  '
+      ? typeof indent === 'number'
+        ? new Array(indent + 1).join(' ') : indent : '  '
     var outputString = ''
     var indentLevel = 0
     var inString

lib/printer.js

@@ -41,7 +41,7 @@
 
     var indentString = options.indent
     if (typeof indentString === 'number') {
-      indentString = ' '.repeat(indentString)
+      indentString = new Array(indentString + 1).join(' ')
     }
     // Setting the indent to an empty string enables pretty-printing too.
     // It will just insert line breaks without any indentation.