Ruby: Fixed exponential backtracking (#2225)

This fixes the exponential backtracking in one of Ruby's regex patterns.

components/prism-ruby.js

@@ -2,9 +2,9 @@
  * Original by Samuel Flores
  *
  * Adds the following new token classes:
- * 		constant, builtin, variable, symbol, regex
+ *     constant, builtin, variable, symbol, regex
  */
-(function(Prism) {
+(function (Prism) {
 	Prism.languages.ruby = Prism.languages.extend('clike', {
 		'comment': [
 			/#.*/,
@@ -13,13 +13,13 @@
 				greedy: true
 			}
 		],
-    'class-name': {
-      pattern: /(\b(?:class)\s+|\bcatch\s+\()[\w.\\]+/i,
-      lookbehind: true,
-      inside: {
-        'punctuation': /[.\\]/
-      }
-    },
+		'class-name': {
+			pattern: /(\b(?:class)\s+|\bcatch\s+\()[\w.\\]+/i,
+			lookbehind: true,
+			inside: {
+				'punctuation': /[.\\]/
+			}
+		},
 		'keyword': /\b(?:alias|and|BEGIN|begin|break|case|class|def|define_method|defined|do|each|else|elsif|END|end|ensure|extend|for|if|in|include|module|new|next|nil|not|or|prepend|protected|private|public|raise|redo|require|rescue|retry|return|self|super|then|throw|undef|unless|until|when|while|yield)\b/
 	});
 
@@ -75,7 +75,7 @@
 				}
 			},
 			{
-				pattern: /(^|[^/])\/(?!\/)(?:\[.+?]|\\.|[^/\\\r\n])+\/[gim]{0,3}(?=\s*(?:$|[\r\n,.;})]))/,
+				pattern: /(^|[^/])\/(?!\/)(?:\[[^\r\n\]]+\]|\\.|[^[/\\\r\n])+\/[gim]{0,3}(?=\s*(?:$|[\r\n,.;})]))/,
 				lookbehind: true,
 				greedy: true
 			}