Added tests to previously broken functionality and added null checks.

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 107961528981c75dd7f9ad625c29bfcb507a9ebc..92e02de50ef877ac1d71af39afd037f832fdcf74 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -1203,9 +1203,11 @@ class CanvasRenderingContext2D extends CanvasRenderingContext native "CanvasRend
       _putImageData_1(imagedata_1, dx, dy);
       return;
     }
-    var imagedata_2 = _convertDartToNative_ImageData(imagedata);
-    _putImageData_2(imagedata_2, dx, dy, dirtyX, dirtyY, dirtyWidth, dirtyHeight);
-    return;
+    if (dirtyHeight != null && dirtyWidth != null && dirtyY != null && dirtyX != null) {
+      var imagedata_2 = _convertDartToNative_ImageData(imagedata);
+      _putImageData_2(imagedata_2, dx, dy, dirtyX, dirtyY, dirtyWidth, dirtyHeight);
+      return;
+    }
     throw new ArgumentError("Incorrect number or type of arguments");
   }
   @JSName('putImageData')
@@ -1298,9 +1300,11 @@ class CanvasRenderingContext2D extends CanvasRenderingContext native "CanvasRend
       _putImageDataHD_1(imagedata_1, dx, dy);
       return;
     }
-    var imagedata_2 = _convertDartToNative_ImageData(imagedata);
-    _putImageDataHD_2(imagedata_2, dx, dy, dirtyX, dirtyY, dirtyWidth, dirtyHeight);
-    return;
+    if (dirtyHeight != null && dirtyWidth != null && dirtyY != null && dirtyX != null) {
+      var imagedata_2 = _convertDartToNative_ImageData(imagedata);
+      _putImageDataHD_2(imagedata_2, dx, dy, dirtyX, dirtyY, dirtyWidth, dirtyHeight);
+      return;
+    }
     throw new ArgumentError("Incorrect number or type of arguments");
   }
   @JSName('webkitPutImageDataHD')
@@ -13647,10 +13651,10 @@ class MediaStream extends EventTarget native "MediaStream" {
     if (!?stream_OR_tracks) {
       return MediaStream._create_1();
     }
-    if ((stream_OR_tracks is MediaStream || stream_OR_tracks == null)) {
+    if (stream_OR_tracks is MediaStream && stream_OR_tracks != null) {
       return MediaStream._create_2(stream_OR_tracks);
     }
-    if ((stream_OR_tracks is List<MediaStreamTrack> || stream_OR_tracks == null)) {
+    if (stream_OR_tracks is List<MediaStreamTrack> && stream_OR_tracks != null) {
       return MediaStream._create_3(stream_OR_tracks);
     }
     throw new ArgumentError("Incorrect number or type of arguments");
@@ -16035,10 +16039,10 @@ class Path native "Path" {
     if (!?path_OR_text) {
       return Path._create_1();
     }
-    if ((path_OR_text is Path || path_OR_text == null)) {
+    if (path_OR_text is Path && path_OR_text != null) {
       return Path._create_2(path_OR_text);
     }
-    if ((path_OR_text is String || path_OR_text == null)) {
+    if (path_OR_text is String && path_OR_text != null) {
       return Path._create_3(path_OR_text);
     }
     throw new ArgumentError("Incorrect number or type of arguments");
@@ -20723,13 +20727,13 @@ class WebSocket extends EventTarget native "WebSocket" {
   @DomName('WebSocket.WebSocket')
   @DocsEditable
   factory WebSocket(String url, [protocol_OR_protocols]) {
-    if ((url is String || url == null) && !?protocol_OR_protocols) {
+    if (url is String && !?protocol_OR_protocols) {
       return WebSocket._create_1(url);
     }
-    if ((url is String || url == null) && (protocol_OR_protocols is List<String> || protocol_OR_protocols == null)) {
+    if (protocol_OR_protocols is List<String> && protocol_OR_protocols != null && url is String) {

[blois, 2013/05/13 21:09:16]

why are the "url is String" checks here- it's typed and it's not optional.

[Andrei Mouravski, 2013/05/14 00:00:53]

Because that's what the code does? It was being checked before, too.

       return WebSocket._create_2(url, protocol_OR_protocols);
     }
-    if ((url is String || url == null) && (protocol_OR_protocols is String || protocol_OR_protocols == null)) {
+    if (protocol_OR_protocols is String && protocol_OR_protocols != null && url is String) {
       return WebSocket._create_3(url, protocol_OR_protocols);
     }
     throw new ArgumentError("Incorrect number or type of arguments");