parser.spec.js: Fix comment typo

spec/unit/parser.spec.js

@@ -330,7 +330,7 @@ describe("PEG.js grammar parser", function() {
     expect("start = !'abcd'?").toParseAs(oneRuleGrammar(simpleNotOptional));
   });
 
-  // Canonical SuffixedExpression is "'ebcd'?".
+  // Canonical SuffixedExpression is "'abcd'?".
   it("parses SuffixedExpression", function() {
     expect("start = 'abcd'\n?").toParseAs(oneRuleGrammar(optional));
     expect("start = 'abcd'"   ).toParseAs(oneRuleGrammar(literalAbcd));