Remove generated directories with 100s of files.

client/html/generated/html/frog/MutationEvent.dart

Index: client/html/generated/html/frog/MutationEvent.dart
diff --git a/client/html/generated/html/frog/MutationEvent.dart b/client/html/generated/html/frog/MutationEvent.dart
deleted file mode 100644
index 2dfb5b6f0f983b19eca0b02875084e9a23dc21cb..0000000000000000000000000000000000000000
--- a/client/html/generated/html/frog/MutationEvent.dart
+++ /dev/null
@@ -1,21 +0,0 @@
-
-class _MutationEventImpl extends _EventImpl implements MutationEvent native "*MutationEvent" {
-
-  static final int ADDITION = 2;
-
-  static final int MODIFICATION = 1;
-
-  static final int REMOVAL = 3;
-
-  final int attrChange;
-
-  final String attrName;
-
-  final String newValue;
-
-  final String prevValue;
-
-  final _NodeImpl relatedNode;
-
-  void initMutationEvent(String type, bool canBubble, bool cancelable, _NodeImpl relatedNode, String prevValue, String newValue, String attrName, int attrChange) native;
-}