Add custom annotations to some APIs for native tree shaking.

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 283b1c82b2e471ea99417c66c24ff7a260ca1120..24b5d24d88e77afc5482a1dde54e672acb87a2a6 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -4927,7 +4927,9 @@ class CanvasRenderingContext2D extends CanvasRenderingContext native "*CanvasRen
     }
     throw const Exception("Incorrect number or type of arguments");
   }
+  @Creates('ImageData|=Object')
   _createImageData_1(imagedata) native "createImageData";
+  @Creates('ImageData|=Object')
   _createImageData_2(num sw, sh) native "createImageData";
 
   /** @domName CanvasRenderingContext2D.createLinearGradient */
@@ -4958,6 +4960,7 @@ class CanvasRenderingContext2D extends CanvasRenderingContext native "*CanvasRen
   ImageData getImageData(num sx, num sy, num sw, num sh) {
     return _convertNativeToDart_ImageData(_getImageData_1(sx, sy, sw, sh));
   }
+  @Creates('ImageData|=Object')
   _getImageData_1(sx, sy, sw, sh) native "getImageData";
 
   /** @domName CanvasRenderingContext2D.getLineDash */
@@ -5057,6 +5060,7 @@ class CanvasRenderingContext2D extends CanvasRenderingContext native "*CanvasRen
   ImageData webkitGetImageDataHD(num sx, num sy, num sw, num sh) {
     return _convertNativeToDart_ImageData(_webkitGetImageDataHD_1(sx, sy, sw, sh));
   }
+  @Creates('ImageData|=Object')
   _webkitGetImageDataHD_1(sx, sy, sw, sh) native "webkitGetImageDataHD";
 
   /** @domName CanvasRenderingContext2D.webkitPutImageDataHD */
@@ -6785,6 +6789,9 @@ class DocumentFragment extends Node native "*DocumentFragment" {
   factory DocumentFragment.svg(String svgContent) =>
       new _DocumentFragmentFactoryProvider.createDocumentFragment_svg(svgContent);
 
+  // This is a field of a native object, but used only from Dart code, so does
+  // not instantiate any native classes.
+  @Creates('Null')
   List<Element> _elements;
 
   List<Element> get elements {
@@ -8763,6 +8770,7 @@ class FileReader extends EventTarget native "*FileReader" {
   final int readyState;
 
   /** @domName FileReader.result */
+  @Creates('String|ArrayBuffer|Null')
   final Object result;
 
   /** @domName FileReader.abort */
@@ -9827,6 +9835,7 @@ class HttpRequest extends EventTarget native "*XMLHttpRequest" {
   final int readyState;
 
   /** @domName XMLHttpRequest.response */
+  @Creates('ArrayBuffer|Blob|Document|=Object|=List|String|num')
   final Object response;
 
   /** @domName XMLHttpRequest.responseText */
@@ -10004,6 +10013,7 @@ class IDBCursor native "*IDBCursor" {
   final String direction;
 
   /** @domName IDBCursor.key */
+  @annotation_Creates_IDBKey @annotation_Returns_IDBKey
   final Object key;
 
   /** @domName IDBCursor.primaryKey */
@@ -10047,6 +10057,7 @@ class IDBCursor native "*IDBCursor" {
 class IDBCursorWithValue extends IDBCursor native "*IDBCursorWithValue" {
 
   /** @domName IDBCursorWithValue.value */
+  @annotation_Creates_SerializedScriptValue @annotation_Returns_SerializedScriptValue
   final Object value;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
@@ -10222,6 +10233,7 @@ class IDBFactory native "*IDBFactory" {
   IDBVersionChangeRequest deleteDatabase(String name) native;
 
   /** @domName IDBFactory.open */
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBDatabase')
   IDBOpenDBRequest open(String name, [int version]) native;
 
   /** @domName IDBFactory.webkitGetDatabaseNames */
@@ -10279,7 +10291,9 @@ class IDBIndex native "*IDBIndex" {
     }
     throw const Exception("Incorrect number or type of arguments");
   }
+  @Returns('IDBRequest') @Creates('IDBRequest') @annotation_Creates_SerializedScriptValue
   IDBRequest _get_1(IDBKeyRange key) native "get";
+  @Returns('IDBRequest') @Creates('IDBRequest') @annotation_Creates_SerializedScriptValue
   IDBRequest _get_2(key) native "get";
 
   /** @domName IDBIndex.getKey */
@@ -10293,7 +10307,9 @@ class IDBIndex native "*IDBIndex" {
     }
     throw const Exception("Incorrect number or type of arguments");
   }
+  @Returns('IDBRequest') @Creates('IDBRequest') @annotation_Creates_SerializedScriptValue @Creates('IDBObjectStore')
   IDBRequest _getKey_1(IDBKeyRange key) native "getKey";
+  @Returns('IDBRequest') @Creates('IDBRequest') @annotation_Creates_SerializedScriptValue @Creates('IDBObjectStore')
   IDBRequest _getKey_2(key) native "getKey";
 
   /** @domName IDBIndex.openCursor */
@@ -10320,10 +10336,15 @@ class IDBIndex native "*IDBIndex" {
     }
     throw const Exception("Incorrect number or type of arguments");
   }
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBCursor')
   IDBRequest _openCursor_1() native "openCursor";
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBCursor')
   IDBRequest _openCursor_2(IDBKeyRange range) native "openCursor";
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBCursor')
   IDBRequest _openCursor_3(IDBKeyRange range, direction) native "openCursor";
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBCursor')
   IDBRequest _openCursor_4(key) native "openCursor";
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBCursor')
   IDBRequest _openCursor_5(key, direction) native "openCursor";
 
   /** @domName IDBIndex.openKeyCursor */
@@ -10350,10 +10371,15 @@ class IDBIndex native "*IDBIndex" {
     }
     throw const Exception("Incorrect number or type of arguments");
   }
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBCursor')
   IDBRequest _openKeyCursor_1() native "openKeyCursor";
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBCursor')
   IDBRequest _openKeyCursor_2(IDBKeyRange range) native "openKeyCursor";
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBCursor')
   IDBRequest _openKeyCursor_3(IDBKeyRange range, direction) native "openKeyCursor";
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBCursor')
   IDBRequest _openKeyCursor_4(key) native "openKeyCursor";
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBCursor')
   IDBRequest _openKeyCursor_5(key, direction) native "openKeyCursor";
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
@@ -10496,7 +10522,9 @@ class IDBObjectStore native "*IDBObjectStore" {
     var value_3 = _convertDartToNative_SerializedScriptValue(value);
     return _add_2(value_3);
   }
+  @Returns('IDBRequest') @Creates('IDBRequest') @annotation_Creates_IDBKey
   IDBRequest _add_1(value, key) native "add";
+  @Returns('IDBRequest') @Creates('IDBRequest') @annotation_Creates_IDBKey
   IDBRequest _add_2(value) native "add";
 
   /** @domName IDBObjectStore.clear */
@@ -10575,7 +10603,9 @@ class IDBObjectStore native "*IDBObjectStore" {
     }
     throw const Exception("Incorrect number or type of arguments");
   }
+  @Returns('IDBRequest') @Creates('IDBRequest') @annotation_Creates_SerializedScriptValue
   IDBRequest _getObject_1(IDBKeyRange key) native "get";
+  @Returns('IDBRequest') @Creates('IDBRequest') @annotation_Creates_SerializedScriptValue
   IDBRequest _getObject_2(key) native "get";
 
   /** @domName IDBObjectStore.index */
@@ -10605,10 +10635,15 @@ class IDBObjectStore native "*IDBObjectStore" {
     }
     throw const Exception("Incorrect number or type of arguments");
   }
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBCursor')
   IDBRequest _openCursor_1() native "openCursor";
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBCursor')
   IDBRequest _openCursor_2(IDBKeyRange range) native "openCursor";
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBCursor')
   IDBRequest _openCursor_3(IDBKeyRange range, direction) native "openCursor";
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBCursor')
   IDBRequest _openCursor_4(key) native "openCursor";
+  @Returns('IDBRequest') @Creates('IDBRequest') @Creates('IDBCursor')
   IDBRequest _openCursor_5(key, direction) native "openCursor";
 
   /** @domName IDBObjectStore.put */
@@ -10621,7 +10656,9 @@ class IDBObjectStore native "*IDBObjectStore" {
     var value_3 = _convertDartToNative_SerializedScriptValue(value);
     return _put_2(value_3);
   }
+  @Returns('IDBRequest') @Creates('IDBRequest') @annotation_Creates_IDBKey
   IDBRequest _put_1(value, key) native "put";
+  @Returns('IDBRequest') @Creates('IDBRequest') @annotation_Creates_IDBKey
   IDBRequest _put_2(value) native "put";
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
@@ -10674,6 +10711,7 @@ class IDBRequest extends EventTarget native "*IDBRequest" {
   dynamic get _result => JS("dynamic", "#.result", this);
 
   /** @domName IDBRequest.source */
+  @Creates('Null')
   final dynamic source;
 
   /** @domName IDBRequest.transaction */
@@ -15950,6 +15988,7 @@ class SQLResultSetRowList implements JavaScriptIndexingBehavior, List<Map> nativ
   Map item(int index) {
     return _convertNativeToDart_Dictionary(_item_1(index));
   }
+  @Creates('=Object')
   _item_1(index) native "item";
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
@@ -24458,7 +24497,7 @@ _convertDartToNative_ImageData(ImageData imageData) {
 Map _convertNativeToDart_Dictionary(object) {
   if (object == null) return null;
   var dict = {};
-  for (final key in JS('List', 'Object.getOwnPropertyNames(#)', object)) {
+  for (final key in JS('=List', 'Object.getOwnPropertyNames(#)', object)) {
     dict[key] = JS('var', '#[#]', object, key);
   }
   return dict;
@@ -24635,7 +24674,7 @@ _convertDartToNative_PrepareForStructuredClone(value) {
       var copy = readSlot(slot);
       if (copy != null) {
         if (true == copy) {  // Cycle, so commit to making a copy.
-          copy = JS('List', 'new Array(#)', length);
+          copy = JS('=List', 'new Array(#)', length);
           writeSlot(slot, copy);
         }
         return copy;
@@ -24655,7 +24694,7 @@ _convertDartToNative_PrepareForStructuredClone(value) {
           if (!identical(elementCopy, element)) {
             copy = readSlot(slot);   // Cyclic reference may have created it.
             if (true == copy) {
-              copy = JS('List', 'new Array(#)', length);
+              copy = JS('=List', 'new Array(#)', length);
               writeSlot(slot, copy);
             }
             for (int j = 0; j < i; j++) {
@@ -24672,7 +24711,7 @@ _convertDartToNative_PrepareForStructuredClone(value) {
         }
       } else {
         // Not a JavaScript Array.  We are forced to make a copy.
-        copy = JS('List', 'new Array(#)', length);
+        copy = JS('=List', 'new Array(#)', length);
         writeSlot(slot, copy);
       }
 
@@ -24752,7 +24791,7 @@ _convertNativeToDart_AcceptStructuredClone(object, {mustCopy = false}) {
       copy = {};
 
       writeSlot(slot, copy);
-      for (final key in JS('List', 'Object.keys(#)', e)) {
+      for (final key in JS('=List', 'Object.keys(#)', e)) {
         copy[key] = walk(JS('var', '#[#]', e, key));
       }
       return copy;
@@ -24766,7 +24805,7 @@ _convertNativeToDart_AcceptStructuredClone(object, {mustCopy = false}) {
       int length = e.length;
       // Since a JavaScript Array is an instance of Dart List, we can modify it
       // in-place unless we must copy.
-      copy = mustCopy ? JS('List', 'new Array(#)', length) : e;
+      copy = mustCopy ? JS('=List', 'new Array(#)', length) : e;
       writeSlot(slot, copy);
 
       for (int i = 0; i < length; i++) {
@@ -24792,6 +24831,24 @@ bool _isJavaScriptSimpleObject(value) =>
     JS('bool', 'Object.getPrototypeOf(#) === Object.prototype', value);
 bool _isImmutableJavaScriptArray(value) =>
     JS('bool', r'!!(#.immutable$list)', value);
+
+
+
+const String _serializedScriptValue =
+    'num|String|bool|'
+    '=List|=Object|'
+    'Blob|File|ArrayBuffer|ArrayBufferView'
+    // TODO(sra): Add Date, RegExp.
+    ;
+
+const annotation_Creates_SerializedScriptValue =
+    const Creates(_serializedScriptValue);
+const annotation_Returns_SerializedScriptValue =
+    const Returns(_serializedScriptValue);
+
+const String _idbKey = '=List|=Object|num|String';  // TODO(sra): Add Date.
+const annotation_Creates_IDBKey = const Creates(_idbKey);
+const annotation_Returns_IDBKey = const Returns(_idbKey);
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.