When inlining imports from head, put them inside a hidden div

pkg/polymer/lib/src/build/linter.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// Logic to validate that developers are correctly using Polymer constructs.
 /// This is mainly used to produce warnings for feedback in the editor.
 library polymer.src.build.linter;
 
 import 'dart:async';
 import 'dart:convert';
@@ skipping 370 matching lines @@
             {'tag': customTagName, 'base': nodeTag}), span: node.sourceSpan);
       return;
     }
 
     if (hasIsAttribute && baseTag != nodeTag) {
       _logger.warning(BAD_INSTANTIATION_WRONG_BASE_TAG.create(
             {'tag': customTagName, 'base': baseTag}), span: node.sourceSpan);
     }
 
     // FOUC check, if content is supplied
-    if (!node.innerHtml.isEmpty) {
+    if (_isEntryPoint && !node.innerHtml.isEmpty) {
       var parent = node;
       var hasFoucFix = false;
       while (parent != null && !hasFoucFix) {
         if (parent.localName == 'polymer-element' ||
             parent.attributes['unresolved'] != null) {
           hasFoucFix = true;
         }
         if (parent.localName == 'body') break;
         parent = parent.parent;
       }
@@ skipping 46 matching lines @@
     upDirCount = segments.length - 2;
   }
   var reachOutPrefix = '../' * upDirCount;
   return USE_POLYMER_HTML.create({'reachOutPrefix': reachOutPrefix});
 }
 
 const List<String> INTERNALLY_DEFINED_ELEMENTS = 
     const ['auto-binding-dart', 'polymer-element'];
 const List<String> AUTO_BINDING_ELEMENTS =
     const ['auto-binding-dart', 'auto-binding'];