Practically remove boot.js, adds the initialization from the Dart side of

pkg/polymer/lib/src/loader.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.
 
 part of polymer;
 
 /** Annotation used to automatically register polymer elements. */
 class CustomTag {
   final String tagName;
   const CustomTag(this.tagName);
 }
 
 /**
  * Metadata used to label static or top-level methods that are called
  * automatically when loading the library of a custom element.
  */
 const initMethod = const _InitMethodAnnotation();
 
 /**
  * Initializes a polymer application as follows:
  *   * set up up polling for observable changes
- *   *  initialize MDV
- *   *  for each library in [libraries], register custom elements labeled with
- *      [CustomTag] and invoke the initialization method on it.
+ *   * initialize Model-Driven Views
+ *   * Include some style to prevent flash of unstyled content (FOUC)
+ *   * for each library in [libraries], register custom elements labeled with
+ *      [CustomTag] and invoke the initialization method on it. If [libraries]
+ *      is null, first find all libraries that need to be loaded by scanning for
+ *      HTML imports in the main document.
  *
- * The initialization on each library is either a method named `main` or
- * a top-level function and annotated with [initMethod].
+ * The initialization on each library is a top-level function and annotated with
+ * [initMethod].
  *
- * The urls in [libraries] can be absolute or relative to [srcUrl].
+ * The urls in [libraries] can be absolute or relative to
+ * `currentMirrorSystem().isolate.rootLibrary.uri`.
  */
-void initPolymer(List<String> libraries, [String srcUrl]) {
+void initPolymer([List<String> libraries]) {
   runMicrotask(() {
     // DOM events don't yet go through microtasks, so we catch those here.
     new Timer.periodic(new Duration(milliseconds: 125),
         (_) => performMicrotaskCheckpoint());
 
+    preventFlashOfUnstyledContent();
+
     // TODO(jmesserly): mdv should use initMdv instead of mdv.initialize.
     mdv.initialize();
     document.register(PolymerDeclaration._TAG, PolymerDeclaration);
 
-    for (var lib in libraries) {
-      _loadLibrary(lib, srcUrl);
+    // Note: we synchronously load all libraries because the script invoking
+    // this is run after all HTML imports are resolved.
+    if (libraries == null) {
+      libraries = _discoverScripts(document, window.location.href);
     }
+    _loadLibraries(libraries);
+  });
+}
 
-    Polymer._ready.complete();
+void _loadLibraries(libraries) {
+  for (var lib in libraries) {
+    _loadLibrary(lib);
+  }
+  Polymer._ready.complete();
+}
 
-    // TODO(sigmund): move to boot.dart once it's ready.
-    document.body.style.transition = 'opacity 0.3s';
-    document.body.style.opacity = '1';
-  });
+/**
+ * Walks the HTML import structure to discover all script tags that are
+ * implicitly loaded.
+ */
+List<String> _discoverScripts(Document doc, String baseUri,
+    [Set<Document> seen, List<String> scripts]) {
+  if (seen == null) seen = new Set<Document>();
+  if (scripts == null) scripts = <String>[];
+  if (seen.contains(doc)) return scripts;
+  seen.add(doc);
+
+  var inlinedScriptCount = 0;
+  for (var node in doc.queryAll('script,link[rel="import"]')) {
+    if (node is LinkElement) {
+      _discoverScripts(node.import, node.href, seen, scripts);
+    } else if (node is ScriptElement && node.type == 'application/dart') {
+      var url = node.src;
+      if (url != '') {
+        // TODO(sigmund): consider either normalizing package: urls or add a
+        // warning to let users know about cannonicalization issues.
+        scripts.add(url);
+      } else {
+        // We generate a unique identifier for inlined scripts which we later
+        // translate to the unique identifiers used by Dartium. Dartium uses
+        // line/column number information which we can't compute here.
+        scripts.add('$baseUri:$inlinedScriptCount');
+        inlinedScriptCount++;
+      }
+    }
+  }
+  return scripts;
 }
 
 /** All libraries in the current isolate. */
 final _libs = currentMirrorSystem().libraries;
 
+// TODO(sigmund): explore other (cheaper) ways to resolve URIs relative to the
+// root library (see dartbug.com/12612)
+final _rootUri = currentMirrorSystem().isolate.rootLibrary.uri;
+
+/** Regex that matches urls used to represent inlined scripts. */
+final RegExp _inlineScriptRegExp = new RegExp('\(.*\.html.*\):\([0-9]\+\)');
+
+/**
+ * Map URLs fabricated by polymer to URLs fabricated by Dartium to represent
+ * inlined scripts. Polymer uses baseUri:script#, Dartium uses baseUri:line#
+ */
+// TODO(sigmund): figure out if we can generate the same URL and expose it.
+final Map<Uri, List<Uri>> _inlinedScriptMapping = () {
+  var map = {};
+  for (var uri in _libs.keys) {
+    var uriString = uri.toString();
+    var match = _inlineScriptRegExp.firstMatch(uriString);
+    if (match == null) continue;
+    var baseUri = Uri.parse(match.group(1));
+    if (map[baseUri] == null) map[baseUri] = [];
+    map[baseUri].add(uri);
+  }
+  return map;
+}();
+
+/** Returns a new Uri that replaces [path] in [uri]. */
+Uri _replacePath(Uri uri, String path) {
+  return new Uri(scheme: uri.scheme, host: uri.host, port: uri.port,
+      path: path, query: uri.query, fragment: uri.fragment);
+}
+
+/** Returns the Uri in [href] without query parameters or fragments. */
+String _baseUri(String href) {
+  var uri = Uri.parse(window.location.href);
+  var trimUri = new Uri(scheme: uri.scheme, host: uri.host,
+      port: uri.port, path: uri.path);
+  return trimUri.toString();
+}
+
 /**
  * Reads the library at [uriString] (which can be an absolute URI or a relative
- * URI from [srcUrl]), and:
- *
- *   * If present, invokes `main`.
+ * URI from the root library), and:
  *
  *   * If present, invokes any top-level and static functions marked
  *     with the [initMethod] annotation (in the order they appear).
  *
  *   * Registers any [PolymerElement] that is marked with the [CustomTag]
  *     annotation.
  */
-void _loadLibrary(String uriString, [String srcUrl]) {
-  var uri = Uri.parse(uriString);
-  if (uri.scheme == '' && srcUrl != null) {
-    uri = Uri.parse(path.normalize(path.join(path.dirname(srcUrl), uriString)));
+void _loadLibrary(String uriString) {
+  var uri = _rootUri.resolve(uriString);
+  var lib;
+  var match = _inlineScriptRegExp.firstMatch(uriString);
+  if (match != null) {
+    var baseUri = Uri.parse(match.group(1));
+    var list = _inlinedScriptMapping[baseUri];
+    var pos = int.parse(match.group(2), onError: (_) => -1);
+    if (list != null && pos >= 0 && pos < list.length && list[pos] != null) {
+      lib = _libs[list[pos]];
+    }
+  } else {
+    lib = _libs[uri];
   }
-  var lib = _libs[uri];
   if (lib == null) {
     print('warning: $uri library not found');
     return;
   }
 
-  // Invoke `main`, if present.
-  if (lib.functions[#main] != null) {
-    lib.invoke(#main, const []);
-  }
-
   // Search top-level functions marked with @initMethod
   for (var f in lib.functions.values) {
     _maybeInvoke(lib, f);
   }
 
   for (var c in lib.classes.values) {
     // Search for @CustomTag on classes
     for (var m in c.metadata) {
       var meta = m.reflectee;
       if (meta is CustomTag) {
@@ skipping 28 matching lines @@
     print("warning: methods marked with @initMethod should take no "
         "arguments, ${method.simpleName} expects some.");
     return;
   }
   obj.invoke(method.simpleName, const []);
 }
 
 class _InitMethodAnnotation {
   const _InitMethodAnnotation();
 }