Make sure we short-circuit the second corruption test, it might be crashing firefox

sdk/lib/html/dartium/html_dartium.dart

Index: sdk/lib/html/dartium/html_dartium.dart
diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart
index 5eb7ba7fe2551664203de468a67f9b4ac2c2cb6b..e3fd55935e258c7468af046e97643c3861f11a27 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -37076,10 +37076,10 @@ class Url extends NativeFieldWrapperClass2 implements UrlUtils {
     if ((blob_OR_source_OR_stream is Blob || blob_OR_source_OR_stream == null)) {
       return _blink.BlinkURL.instance.createObjectURL_Callback_1_(unwrap_jso(blob_OR_source_OR_stream));
     }
-    if ((blob_OR_source_OR_stream is MediaStream)) {
+    if ((blob_OR_source_OR_stream is MediaSource)) {
       return _blink.BlinkURL.instance.createObjectURL_Callback_1_(unwrap_jso(blob_OR_source_OR_stream));
     }
-    if ((blob_OR_source_OR_stream is MediaSource)) {
+    if ((blob_OR_source_OR_stream is MediaStream)) {
       return _blink.BlinkURL.instance.createObjectURL_Callback_1_(unwrap_jso(blob_OR_source_OR_stream));
     }
     throw new ArgumentError("Incorrect number or type of arguments");
@@ -46857,8 +46857,7 @@ class _ValidatingTreeSanitizer implements NodeTreeSanitizer {
       // On IE, erratically, the hasCorruptedAttributes test can return false,
       // even though it clearly is corrupted. A separate copy of the test
       // inlining just the basic check seems to help.
-      var corruptedTest2 = Element._hasCorruptedAttributesAdditionalCheck(element);
-      corrupted = corruptedTest1 || corruptedTest2;
+      corrupted = corruptedTest1 ? true : Element._hasCorruptedAttributesAdditionalCheck(element);
     } catch(e) {}
     var elementText = 'element unprintable';
     try {