Allow '@import' directives in any selector

Add --strict-imports option to disable for perf
reasons.

Author: cloudhead

bin/lessc

@@ -13,7 +13,8 @@ var options = {
     optimization: 1,
     silent: false,
     paths: [],
-    color: true
+    color: true,
+    strictImports: false
 };
 
 args = args.filter(function (arg) {
@@ -39,6 +40,9 @@ args = args.filter(function (arg) {
         case 'silent':
             options.silent = true;
             break;
+        case 'strict-imports':
+            options.strictImports = true;
+            break;
         case 'h':
         case 'help':
             sys.puts("usage: lessc source [destination]");
@@ -92,7 +96,8 @@ var parseLessFile = function (e, data) {
     new(less.Parser)({
         paths: [path.dirname(input)].concat(options.paths),
         optimization: options.optimization,
-        filename: input
+        filename: input,
+        strictImports: options.strictImports
     }).parse(data, function (err, tree) {
         if (err) {
             less.writeError(err, options);

lib/less/parser.js

@@ -989,7 +989,7 @@ less.Parser = function Parser(env) {
                 }
 
                 if (selectors.length > 0 && (rules = $(this.block))) {
-                    return new(tree.Ruleset)(selectors, rules);
+                    return new(tree.Ruleset)(selectors, rules, env.strictImports);
                 } else {
                     // Backtrack
                     furthest = i;

lib/less/tree/ruleset.js

@@ -1,14 +1,15 @@
 (function (tree) {
 
-tree.Ruleset = function (selectors, rules) {
+tree.Ruleset = function (selectors, rules, strictImports) {
     this.selectors = selectors;
     this.rules = rules;
     this._lookups = {};
+    this.strictImports = strictImports;
 };
 tree.Ruleset.prototype = {
     eval: function (env) {
         var selectors = this.selectors && this.selectors.map(function (s) { return s.eval(env) });
-        var ruleset = new(tree.Ruleset)(selectors, this.rules.slice(0));
+        var ruleset = new(tree.Ruleset)(selectors, this.rules.slice(0), this.strictImports);
 
         ruleset.root = this.root;
         ruleset.allowImports = this.allowImports;
@@ -17,7 +18,7 @@ tree.Ruleset.prototype = {
         env.frames.unshift(ruleset);
 
         // Evaluate imports
-        if (ruleset.root || ruleset.allowImports) {
+        if (ruleset.root || ruleset.allowImports || !ruleset.strictImports) {
             for (var i = 0; i < ruleset.rules.length; i++) {
                 if (ruleset.rules[i] instanceof tree.Import) {
                     Array.prototype.splice