[ruby mode] Make else and elsif electric

Closes codemirror#4345

Author: marijnh

mode/ruby/ruby.js

@@ -275,7 +275,7 @@ CodeMirror.defineMode("ruby", function(config) {
         (state.continuedLine ? config.indentUnit : 0);
     },
 
-    electricInput: /^\s*(?:end|rescue|\})$/,
+    electricInput: /^\s*(?:end|rescue|elsif|else|\})$/,
     lineComment: "#"
   };
 });