Refine types of EventTarget

Most DOM attributes that yield an EventTarget are yielding one that has
already been seen by the program.

Review URL: https://codereview.chromium.org//11411347

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@15703 260f80e4-7a28-3924-810f-c04153c831b5

Author: rakudrama

sdk/lib/html/dart2js/html_dart2js.dart

@@ -7836,7 +7836,7 @@ class Event native "*Event" {
   /// @domName Event.currentTarget; @docsEditable true
   EventTarget get currentTarget => _convertNativeToDart_EventTarget(this._currentTarget);
   @JSName('currentTarget')
-  @Creates('EventTarget|=Object') @Returns('EventTarget|=Object')
+  @Creates('Null') @Returns('EventTarget|=Object')
   final dynamic _currentTarget;
 
   /// @domName Event.defaultPrevented; @docsEditable true
@@ -7851,7 +7851,7 @@ class Event native "*Event" {
   /// @domName Event.target; @docsEditable true
   EventTarget get target => _convertNativeToDart_EventTarget(this._target);
   @JSName('target')
-  @Creates('EventTarget|=Object') @Returns('EventTarget|=Object')
+  @Creates('Node') @Returns('EventTarget|=Object')
   final dynamic _target;
 
   /// @domName Event.timeStamp; @docsEditable true
@@ -13055,7 +13055,7 @@ class MouseEvent extends UIEvent native "*MouseEvent" {
   /// @domName MouseEvent.relatedTarget; @docsEditable true
   EventTarget get relatedTarget => _convertNativeToDart_EventTarget(this._relatedTarget);
   @JSName('relatedTarget')
-  @Creates('EventTarget|=Object') @Returns('EventTarget|=Object')
+  @Creates('Node') @Returns('EventTarget|=Object')
   final dynamic _relatedTarget;
 
   /// @domName MouseEvent.screenX; @docsEditable true
@@ -17454,7 +17454,7 @@ class Touch native "*Touch" {
   /// @domName Touch.target; @docsEditable true
   EventTarget get target => _convertNativeToDart_EventTarget(this._target);
   @JSName('target')
-  @Creates('EventTarget|=Object') @Returns('EventTarget|=Object')
+  @Creates('Element|Document') @Returns('Element|Document')
   final dynamic _target;
 
   /// @domName Touch.webkitForce; @docsEditable true

sdk/lib/html/scripts/generator.py

@@ -594,6 +594,7 @@ def FindConversion(idl_type, direction, interface, member):
 #
 #   INTERFACE.MEMBER: annotations for member.
 #   +TYPE:            add annotations only if there are member annotations.
+#   -TYPE:            add annotations only if there are no member annotations.
 #   TYPE:             add regardless of member annotations.
 
 dart2js_annotations = {
@@ -615,10 +616,26 @@ def FindConversion(idl_type, direction, interface, member):
     'DOMWindow.openDatabase': "@Creates('Database') @Creates('DatabaseSync')",
 
     # Cross-frame windows are EventTargets.
-    'EventTarget':
-      #"@Creates('Null') @Returns('EventTarget|=Object')",
+    '-EventTarget':
       "@Creates('EventTarget|=Object') @Returns('EventTarget|=Object')",
 
+    # To be in callback with the browser-created Event, we had to have called
+    # addEventListener on the target, so we avoid
+    'Event.currentTarget':
+        "@Creates('Null') @Returns('EventTarget|=Object')",
+
+    # Only nodes in the DOM bubble and have target !== currentTarget.
+    'Event.target':
+        "@Creates('Node') @Returns('EventTarget|=Object')",
+
+    'MouseEvent.relatedTarget':
+        "@Creates('Node') @Returns('EventTarget|=Object')",
+
+    # Touch targets are Elements in a Document, or the Document.
+    'Touch.target':
+        "@Creates('Element|Document') @Returns('Element|Document')",
+
+
     'FileReader.result': "@Creates('String|ArrayBuffer|Null')",
 
     # Rather than have the result of an IDBRequest as a union over all possible
@@ -687,6 +704,9 @@ def FindAnnotations(idl_type, interface_name, member_name):
       return ann2 + ' ' + ann1
     return ann1
 
+  ann2 = dart2js_annotations.get('-' + idl_type)
+  if ann2:
+    return ann2
   ann2 = dart2js_annotations.get(idl_type)
   return ann2