Rework standalone to use a synchronous loader that does not invoke Dart code

runtime/lib/lib_prefix.dart

Index: runtime/lib/lib_prefix.dart
diff --git a/runtime/lib/lib_prefix.dart b/runtime/lib/lib_prefix.dart
index 4f509da5bff4a23e95cbea1eed136bfcd5357576..4d0bb53ae5a584ca9004ce95281149b8f36df964 100644
--- a/runtime/lib/lib_prefix.dart
+++ b/runtime/lib/lib_prefix.dart
@@ -49,16 +49,21 @@ var _outstandingLoadRequests = new List<List>();
 // Called from the VM when all outstanding load requests have
 // finished.
 _completeDeferredLoads() {
+  var stillOutstandingLoadRequests = new List<List>();

[turnidge, 2016/06/03 17:50:25]

Comment?

   for (int i = 0; i < _outstandingLoadRequests.length; i++) {
     var prefix = _outstandingLoadRequests[i][0];
-    var completer = _outstandingLoadRequests[i][1];
-    var error = prefix._loadError();
-    if (error != null) {
-      completer.completeError(error);
+    if (prefix._load()) {
+      var completer = _outstandingLoadRequests[i][1];
+      var error = prefix._loadError();
+      if (error != null) {
+        completer.completeError(error);
+      } else {
+        prefix._invalidateDependentCode();
+        completer.complete(true);
+      }
     } else {
-      prefix._invalidateDependentCode();
-      completer.complete(true);
+      stillOutstandingLoadRequests.add(_outstandingLoadRequests[i]);
     }
   }
-  _outstandingLoadRequests.clear();
+  _outstandingLoadRequests = stillOutstandingLoadRequests;
 }