Split DragEvent back out from MouseEvent

sdk/lib/_blink/dartium/_blink_dartium.dart

Index: sdk/lib/_blink/dartium/_blink_dartium.dart
diff --git a/sdk/lib/_blink/dartium/_blink_dartium.dart b/sdk/lib/_blink/dartium/_blink_dartium.dart
index 3dac59c5988baa42cb0d76d4a4aeace86afc91c8..378063f27872d11d54fcd18c7b2cd48b573efbd2 100644
--- a/sdk/lib/_blink/dartium/_blink_dartium.dart
+++ b/sdk/lib/_blink/dartium/_blink_dartium.dart
@@ -170,6 +170,7 @@ dynamic resolver(String s) {
   if (s == "Document") return BlinkDocument.instance;
   if (s == "DocumentFragment") return BlinkDocumentFragment.instance;
   if (s == "DocumentType") return BlinkDocumentType.instance;
+  if (s == "DragEvent") return BlinkDragEvent.instance;
   if (s == "DynamicsCompressorNode")
     return BlinkDynamicsCompressorNode.instance;
   if (s == "EXTBlendMinMax") return BlinkEXTBlendMinMax.instance;
@@ -7098,6 +7099,22 @@ class BlinkDocumentType extends BlinkNode {
   remove_Callback_0_(mthis) native "Blink_Operation_0_ChildNode_remove";
 }
 
+class BlinkDragEvent extends BlinkMouseEvent {
+  static final instance = new BlinkDragEvent();
+
+  constructorCallback_0_() =>
+      Blink_JsNative_DomException.callConstructor0("DragEvent");
+
+  constructorCallback_1_(__arg_0) =>
+      Blink_JsNative_DomException.callConstructor("DragEvent", [__arg_0]);
+
+  constructorCallback_2_(__arg_0, __arg_1) => Blink_JsNative_DomException
+      .callConstructor("DragEvent", [__arg_0, __arg_1]);
+
+  dataTransfer_Getter_(mthis) => Blink_JsNative_DomException.getProperty(
+      mthis /* DragEvent */, "dataTransfer");
+}
+
 class BlinkDynamicsCompressorNode extends BlinkAudioNode {
   static final instance = new BlinkDynamicsCompressorNode();