Handle Nop statement after brace-style namespace

Fixes #412.

CHANGELOG.md

@@ -1,7 +1,9 @@
 Version 3.1.1-dev
 -----------------
 
-Nothing yet.
+### Fixed
+
+* Fixed syntax error on comment after brace-style namespace declaration. (#412)
 
 Version 3.1.0 (2017-07-28)
 --------------------------

lib/PhpParser/ParserAbstract.php

@@ -445,6 +445,7 @@ abstract class ParserAbstract implements Parser
                 if ($stmt instanceof Node\Stmt\Namespace_) {
                     $afterFirstNamespace = true;
                 } elseif (!$stmt instanceof Node\Stmt\HaltCompiler
+                        && !$stmt instanceof Node\Stmt\Nop
                         && $afterFirstNamespace && !$hasErrored) {
                     $this->emitError(new Error(
                         'No code may exist outside of namespace {}', $stmt->getAttributes()));

test/code/parser/stmt/namespace/commentAfterNamespace.test

@@ -0,0 +1,22 @@
+Trailing comment after braced namespace declaration
+-----
+<?php
+namespace Foo {}
+// Comment
+-----
+array(
+    0: Stmt_Namespace(
+        name: Name(
+            parts: array(
+                0: Foo
+            )
+        )
+        stmts: array(
+        )
+    )
+    1: Stmt_Nop(
+        comments: array(
+            0: // Comment
+        )
+    )
+)