fix alpha(opacity=n) support

lib/less/parser.js

@@ -764,7 +764,7 @@ less.Parser = function Parser(env) {
             alpha: function () {
                 var value;
 
-                if (! $(/^opacity=/i)) return;
+                if (! $(/^\(opacity=/i)) return;
                 if (value = $(/^\d+/) || $(this.entities.variable)) {
                     if (! $(')')) throw new(Error)("missing closing ) for alpha()");
                     return new(tree.Alpha)(value);

lib/less/tree/alpha.js

@@ -8,7 +8,10 @@ tree.Alpha.prototype = {
         return "alpha(opacity=" +
                (this.value.toCSS ? this.value.toCSS() : this.value) + ")";
     },
-    eval: function () { return this }
+    eval: function (env) {
+        if (this.value.eval) { this.value = this.value.eval(env) }
+        return this;
+    }
 };
 
 })(require('less/tree'));

test/css/css.css

@@ -66,6 +66,7 @@ p + h1 {
   background-image: url(images/image.jpg);
   background: -webkit-gradient(linear, left top, left bottom, from(red), to(blue));
   margin: ;
+  filter: alpha(opacity=100);
 }
 #important {
   color: red !important;

test/css/variables.css

@@ -19,3 +19,6 @@
 .variable-names {
   name: 'hello';
 }
+.alpha {
+  filter: alpha(opacity=42);
+}

test/less/css.less

@@ -78,6 +78,7 @@ p + h1 {
   background-image: url(images/image.jpg);
   background: -webkit-gradient(linear, left top, left bottom, from(red), to(blue));
   margin: ;
+  filter: alpha(opacity=100);
 }
 
 #important {

test/less/variables.less

@@ -44,3 +44,7 @@
     @name: 'var';
     name: @@name;
 }
+.alpha {
+    @var: 42;
+    filter: alpha(opacity=@var);
+}