unfork DDC's copy of most SDK libraries

pkg/dev_compiler/tool/input_sdk/private/isolate_helper.dart

Index: pkg/dev_compiler/tool/input_sdk/private/isolate_helper.dart
diff --git a/pkg/dev_compiler/tool/input_sdk/private/isolate_helper.dart b/pkg/dev_compiler/tool/input_sdk/private/isolate_helper.dart
index 975dde740e228a69fa7b3179d31bd02e5f135525..316197c4ea8f9ce68a121290ebe4b9c35c3dcb89 100644
--- a/pkg/dev_compiler/tool/input_sdk/private/isolate_helper.dart
+++ b/pkg/dev_compiler/tool/input_sdk/private/isolate_helper.dart
@@ -382,10 +382,6 @@ class _IsolateContext implements IsolateContext {
       return;
     }
     void respond() { responsePort.send(null); }
-    if (pingType == Isolate.AS_EVENT) {
-      _globalState.topEventLoop.enqueue(this, respond, "ping");
-      return;
-    }
     assert(pingType == Isolate.BEFORE_NEXT_EVENT);
     if (_scheduledControlEvents == null) {
       _scheduledControlEvents = new Queue();
@@ -401,10 +397,6 @@ class _IsolateContext implements IsolateContext {
       kill();
       return;
     }
-    if (priority == Isolate.AS_EVENT) {
-      _globalState.topEventLoop.enqueue(this, kill, "kill");
-      return;
-    }
     assert(priority == Isolate.BEFORE_NEXT_EVENT);
     if (_scheduledControlEvents == null) {
       _scheduledControlEvents = new Queue();
@@ -744,6 +736,14 @@ class IsolateNatives {
 
   static String thisScript = computeThisScript();
 
+  /// Returns the base path added to Uri.base to resolve `package:` Uris.
+  ///
+  /// This is used by `Isolate.resolvePackageUri` to load resources. The default
+  /// value is `packages/` but users can override this by using the
+  /// `defaultPackagesBase` hook.
+  static String get packagesBase =>
+      JS('String', r'self.defaultPackagesBase || "packages/"');
+
   /// Associates an ID with a native worker object.
   static final Expando<int> workerIds = new Expando<int>();