Let deferred load work from worker isolates.

sdk/lib/_internal/lib/async_patch.dart

Index: sdk/lib/_internal/lib/async_patch.dart
diff --git a/sdk/lib/_internal/lib/async_patch.dart b/sdk/lib/_internal/lib/async_patch.dart
index 053e856712e68786fb5cb93344e60daca09c38a0..c26f29f9291e8c5926101078eefd5077c82b9295 100644
--- a/sdk/lib/_internal/lib/async_patch.dart
+++ b/sdk/lib/_internal/lib/async_patch.dart
@@ -4,9 +4,15 @@
 
 // Patch file for the dart:async library.
 
-import 'dart:_js_helper' show Primitives;
-import 'dart:_isolate_helper' show IsolateNatives, TimerImpl;
-import 'dart:_foreign_helper' show JS, DART_CLOSURE_TO_JS;
+import 'dart:_js_helper' show Primitives, convertDartClosureToJS;
+import 'dart:_isolate_helper' show
+    IsolateNatives,
+    TimerImpl,
+    leaveJsAsync,
+    enterJsAsync,
+    isWorker;
+
+import 'dart:_foreign_helper' show JS;
 
 patch Timer _createTimer(Duration duration, void callback()) {
   int milliseconds = duration.inMilliseconds;
@@ -41,7 +47,7 @@ patch class DeferredLibrary {
                        libraryName, index));
     }
     Iterable<Future<bool>> allLoads =
-        hunkNames.map((libraryName) => _load(libraryName, uri));
+        hunkNames.map((hunkName) => _load(hunkName, uri));
     return Future.wait(allLoads).then((results) {
       return results.any((x) => x);
     });
@@ -60,57 +66,88 @@ Future<bool> _load(String hunkName, String uri) {
     return future.then((_) => false);
   }
 
-  if (Primitives.isJsshell) {
-    // TODO(ahe): Move this code to a JavaScript command helper script that is
-    // not included in generated output.
-    return _loadedLibraries[hunkName] = new Future<bool>(() {
-      if (uri == null) uri = '$hunkName';
-      // Create a new function to avoid getting access to current function
-      // context.
-      JS('void', '(new Function(#))()', 'loadRelativeToScript("$uri")');
-      return true;
-    });
-  } else if (Primitives.isD8) {
+  if (uri == null) {
+    uri = IsolateNatives.thisScript;
+  }
+  int index = uri.lastIndexOf('/');
+  uri = '${uri.substring(0, index + 1)}$hunkName';
+
+  if (Primitives.isJsshell || Primitives.isD8) {
     // TODO(ahe): Move this code to a JavaScript command helper script that is
     // not included in generated output.
     return _loadedLibraries[hunkName] = new Future<bool>(() {
-      if (uri == null) {
-        uri = IsolateNatives.computeThisScriptD8();
-        int index = uri.lastIndexOf('/');
-        uri = '${uri.substring(0, index + 1)}$hunkName';
+      try {
+        // Create a new function to avoid getting access to current function
+        // context.
+        JS('void', '(new Function(#))()', 'load("$uri")');
+      } catch (error, stackTrace) {
+        throw new DeferredLoadException("Loading $uri failed.");
       }
-      // Create a new function to avoid getting access to current function
-      // context.
-      JS('void', '(new Function(#))()', 'load("$uri")');
       return true;
     });
-  }
+  } else if (isWorker()) {
+    // We are in a web worker. Load the code with an XMLHttpRequest.
+    return _loadedLibraries[hunkName] = new Future<bool>(() {
+      Completer completer = new Completer<bool>();
+      enterJsAsync();
+      Future<bool> leavingFuture = completer.future.whenComplete(() {
+        leaveJsAsync();
+      });
 
-  return _loadedLibraries[hunkName] = new Future<bool>(() {
-    Completer completer = new Completer<bool>();
-    if (uri == null) {
-      uri = IsolateNatives.thisScript;
       int index = uri.lastIndexOf('/');
       uri = '${uri.substring(0, index + 1)}$hunkName';
-    }
+      var xhr =  JS('dynamic', 'new XMLHttpRequest()');
+      JS('void', '#.open("GET", #)', xhr, uri);
+      JS('void', '#.addEventListener("load", #, false)',
+         xhr, convertDartClosureToJS((event) {
+        if (JS('int', '#.status', xhr) != 200) {
+          completer.completeError(
+              new DeferredLoadException("Loading $uri failed."));
+          return;
+        }
+        String code = JS('String', '#.responseText', xhr);
+        try {
+          // Create a new function to avoid getting access to current function
+          // context.
+          JS('void', '(new Function(#))()', code);
+        } catch (error, stackTrace) {
+          completer.completeError(
+            new DeferredLoadException("Evaluating $uri failed."));
+          return;
+        }
+        completer.complete(true);
+      }, 1));
 
+      var fail = convertDartClosureToJS((event) {
+        new DeferredLoadException("Loading $uri failed.");
+      }, 1);
+      JS('void', '#.addEventListener("error", #, false)', xhr, fail);
+      JS('void', '#.addEventListener("abort", #, false)', xhr, fail);
+
+      JS('void', '#.send()', xhr);
+      return leavingFuture;
+    });
+  }
+  // We are in a dom-context.
+  return _loadedLibraries[hunkName] = new Future<bool>(() {
+    Completer completer = new Completer<bool>();
     // Inject a script tag.
     var script = JS('', 'document.createElement("script")');
     JS('', '#.type = "text/javascript"', script);
     JS('', '#.src = #', script, uri);
-    var onLoad = JS('', '#.bind(null, #)',
-                    DART_CLOSURE_TO_JS(_onDeferredLibraryLoad), completer);
-    JS('', '#.addEventListener("load", #, false)', script, onLoad);
+    JS('', '#.addEventListener("load", #, false)',
+       script, convertDartClosureToJS((event) {
+      completer.complete(true);
+    }, 1));
+    JS('', '#.addEventListener("error", #, false)',
+       script, convertDartClosureToJS((event) {
+      completer.completeError(
+          new DeferredLoadException("Loading $uri failed."));
+    }, 1));
     JS('', 'document.body.appendChild(#)', script);
 
     return completer.future;
   });
 }
 
-/// Used to implement deferred loading. Used as callback on "load"
-/// event above in [load].
-_onDeferredLibraryLoad(Completer<bool> completer, event) {
-  completer.complete(true);
-}
-
 bool get _hasDocument => JS('String', 'typeof document') == 'object';