Make infinite loop and left recursion detectors work with named rules

Add missing |named| case to the visitor in lib/compiler/asts.js, which
makes the infinite loop and left recursion detectors work correctly with
named rules.

The missing case caused |make parser| to fail with:

  140:34: Infinite loop detected.
  make: *** [parser] Error 1

lib/compiler/asts.js

@@ -22,7 +22,8 @@ var asts = {
     }
 
     var advances = visitor.build({
-      rule: advancesExpression,
+      rule:  advancesExpression,
+      named: advancesExpression,
 
       choice: function(node) {
         return arrays.every(node.alternatives, advances);

spec/unit/compiler/passes/report-infinite-loops.spec.js

@@ -26,6 +26,15 @@ describe("compiler pass |reportInfiniteLoops|", function() {
   });
 
   it("computes empty string matching correctly", function() {
+    expect(pass).toReportError([
+      'start = a*',
+      'a "a" = ""'
+    ].join('\n'));
+    expect(pass).not.toReportError([
+      'start = a*',
+      'a "a" = "a"'
+    ].join('\n'));
+
     expect(pass).toReportError('start = ("" / "a" / "b")*');
     expect(pass).toReportError('start = ("a" / "" / "b")*');
     expect(pass).toReportError('start = ("a" / "b" / "")*');

spec/unit/compiler/passes/report-left-recursion.spec.js

@@ -40,6 +40,15 @@ describe("compiler pass |reportLeftRecursion|", function() {
     });
 
     it("computes empty string matching correctly", function() {
+      expect(pass).toReportError([
+        'start = a start',
+        'a "a" = ""'
+      ].join('\n'));
+      expect(pass).not.toReportError([
+        'start = a start',
+        'a "a" = "a"'
+      ].join('\n'));
+
       expect(pass).toReportError('start = ("" / "a" / "b") start');
       expect(pass).toReportError('start = ("a" / "" / "b") start');
       expect(pass).toReportError('start = ("a" / "b" / "") start');