don't move anything to body until first import

pkg/polymer/lib/src/build/import_inliner.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.
 
 /// Transfomer that inlines polymer-element definitions from html imports.
 library polymer.src.build.import_inliner;
 
 import 'dart:async';
 import 'dart:convert';
 
@@ skipping 44 matching lines @@
 
     return readPrimaryAsHtml(transform, logger).then((doc) {
       document = doc;
 
       // Insert our importsWrapper. This may be removed later if not needed, but
       // it makes the logic simpler to have it in the document.
       document.body.insertBefore(importsWrapper, document.body.firstChild);
 
       changed = new _UrlNormalizer(transform, docId, logger).visit(document)
         || changed;
-      
+
       experimentalBootstrap = document.querySelectorAll('link').any((link) =>
           link.attributes['rel'] == 'import' &&
           link.attributes['href'] == POLYMER_EXPERIMENTAL_HTML);
       changed = _extractScripts(document) || changed;
 
       // We only need to move the head into the body for the entry point.
       _moveHeadToBody(document);
 
       return _visitImports(document);
     }).then((importsFound) {
@@ skipping 59 matching lines @@
         if (!options.shouldInlineStylesheet(id)) return null;
 
         changed = true;
         return _inlineStylesheet(id, tag);
       }
     }).then((_) => changed);
   }
 
   /// To preserve the order of scripts with respect to inlined
   /// link rel=import, we move both of those into the body before we do any
-  /// inlining.
+  /// inlining. We do not start doing this until the first import is found
+  /// however, as some scripts do need to be ran in the head to work
+  /// properly (platform.js for instance).
   ///
   /// Note: we do this for stylesheets as well to preserve ordering with
   /// respect to eachother, because stylesheets can be pulled in transitively
   /// from imports.
   // TODO(jmesserly): vulcanizer doesn't need this because they inline JS
   // scripts, causing them to be naturally moved as part of the inlining.
   // Should we do the same? Alternatively could we inline head into head and
   // body into body and avoid this whole thing?
   void _moveHeadToBody(Document doc) {
+    var foundImport = false;
     for (var node in doc.head.nodes.toList(growable: false)) {
       if (node is! Element) continue;
       var tag = node.localName;
       var type = node.attributes['type'];
       var rel = node.attributes['rel'];
+      if (tag == 'link' && rel == 'import') foundImport = true;
+      if (!foundImport) continue;
       if (tag == 'style' || tag == 'script' &&
             (type == null || type == TYPE_JS || type == TYPE_DART) ||
           tag == 'link' && (rel == 'stylesheet' || rel == 'import')) {
         // Move the node into the importsWrapper, where its contents will be
         // placed. This wrapper is a hidden div to prevent inlined html from
         // causing a FOUC.
         importsWrapper.append(node);
       }
     }
   }
@@ skipping 369 matching lines @@
 /// style tag except these ones.
 const IGNORED_LINKED_STYLE_ATTRS =
     const ['charset', 'href', 'href-lang', 'rel', 'rev'];
 
 /// Global RegExp objects.
 final _INVALID_LIB_CHARS_REGEX = new RegExp('[^a-z0-9_]');
 final _NUM_REGEX = new RegExp('[0-9]');
 final _BINDING_REGEX = new RegExp(r'(({{.*}})|(\[\[.*\]\]))');
 
 _getSpan(SourceFile file, AstNode node) => file.span(node.offset, node.end);