Update haml-coffee to fix some broken non boolean attributes.

Non boolean values where the key was the same like the value were
wrongly detected as boolean attributes.

In addition empty attributes are allowed also.

This fixes #8.

lib/js/haml-coffee.js

@@ -693,17 +693,19 @@ require.define("/nodes/haml.js", function (require, module, exports, __dirname,
     };
 
     Haml.prototype.parseAttributes = function(exp) {
-      var attributes, datas, findAttributes, key, match, quoted, value, _ref;
+      var attributes, bool, datas, findAttributes, key, match, quoted, value, _ref;
       attributes = [];
       if (exp === void 0) return attributes;
       _ref = this.getDataAttributes(exp), exp = _ref[0], datas = _ref[1];
       findAttributes = /(?:(\w+[\w:-]*\w?|'\w+[\w:-]*\w?'|"\w+[\w:-]*\w?")\s*=\s*("(?:\\.|[^"\\])*"|'(?:\\.|[^'\\])*'|[\w@.]+)|(:\w+[\w:-]*\w?|'\w+[\w:-]*\w?'|"\w+[\w:-]*\w?")\s*=>\s*("(?:\\.|[^"\\])*"|'(?:\\.|[^'\\])*'|[-\w@.()\[\]'"]+)|(\w+[\w:-]*\w?|'\w+[\w:-]*\w?'|'\w+[\w:-]*\w?'):\s*("(?:\\.|[^"\\])*"|'(?:\\.|[^'\\])*'|[-\w@.()\[\]'"]+))/g;
       while (match = findAttributes.exec(exp)) {
         key = (match[1] || match[3] || match[5]).replace(/^:/, '');
         value = match[2] || match[4] || match[6];
-        if (['false', '', '""', "''"].indexOf(value) === -1) {
+        bool = false;
+        if (['false', ''].indexOf(value) === -1) {
           if (['true'].indexOf(value) !== -1) {
             value = "'" + key + "'";
+            bool = true;
           } else if (!value.match(/^("|').*\1$/)) {
             if (this.escapeAttributes) {
               value = '\'#{ e(' + value + ') }\'';
@@ -715,7 +717,8 @@ require.define("/nodes/haml.js", function (require, module, exports, __dirname,
           if (quoted = key.match(/^("|')(.*)\1$/)) key = quoted[2];
           attributes.push({
             key: key,
-            value: value
+            value: value,
+            bool: bool
           });
         }
       }
@@ -760,10 +763,10 @@ require.define("/nodes/haml.js", function (require, module, exports, __dirname,
         _ref2 = tokens.attributes;
         for (_j = 0, _len2 = _ref2.length; _j < _len2; _j++) {
           attribute = _ref2[_j];
-          if (attribute.key !== attribute.value || this.format !== 'html5') {
-            tagParts.push("" + attribute.key + "=" + (this.quoteAttributeValue(attribute.value)));
-          } else {
+          if (attribute.bool && this.format === 'html5') {
             tagParts.push("" + attribute.key);
+          } else {
+            tagParts.push("" + attribute.key + "=" + (this.quoteAttributeValue(attribute.value)));
           }
         }
       }