generate-js.js: Quote the "class" key in DESCRIBE_EXPECTATION_FNS

"class" is a reserved word. Having it as a key unquoted broke IE 8 (both
in standards and quirks mode) and IE 9 (in quirks mode).

lib/compiler/passes/generate-js.js

@@ -788,7 +788,7 @@ function generateJS(ast, options) {
       '          return "\\\"" + literalEscape(expectation.text) + "\\\"";',
       '        },',
       '',
-      '        class: function(expectation) {',
+      '        "class": function(expectation) {',
       '          var escapedParts = "",',
       '              i;',
       '',

lib/parser.js

@@ -35,7 +35,7 @@ peg$SyntaxError.buildMessage = function(expected, found) {
           return "\"" + literalEscape(expectation.text) + "\"";
         },
 
-        class: function(expectation) {
+        "class": function(expectation) {
           var escapedParts = "",
               i;