Use and add layout tests for BCP 47 language tag syntax validation.

LayoutTests/http/tests/media/media-source/mediasource-trackdefault.html

Index: LayoutTests/http/tests/media/media-source/mediasource-trackdefault.html
diff --git a/LayoutTests/http/tests/media/media-source/mediasource-trackdefault.html b/LayoutTests/http/tests/media/media-source/mediasource-trackdefault.html
index 61dcd786e194baed09f04f75c7706accf63e62ac..008082a72fa9b9939d2c87f487571ee4f943f59d 100644
--- a/LayoutTests/http/tests/media/media-source/mediasource-trackdefault.html
+++ b/LayoutTests/http/tests/media/media-source/mediasource-trackdefault.html
@@ -19,9 +19,9 @@
                 assert_array_equals(trackDefault.kinds, kinds, "kinds");
             }
 
-            function checkConstructionFails(type, language, label, kinds, byteStreamTrackID)
+            function checkConstructionFails(type, language, label, kinds, byteStreamTrackID, expectedException)
             {
-                assert_throws(new TypeError(),
+                assert_throws(expectedException,
                     function() { new TrackDefault(type, language, label, kinds, byteStreamTrackID); },
                     "TrackDefault construction threw an exception");
             }
@@ -33,7 +33,7 @@
                     if (expectation)
                         checkConstructionSucceeds(type, language, label, kinds, byteStreamTrackID);
                     else
-                        checkConstructionFails(type, language, label, kinds, byteStreamTrackID);
+                        checkConstructionFails(type, language, label, kinds, byteStreamTrackID, new TypeError());
                 }, description + ": type '" + type + "', language '" + language + "', label '" + label + "', multiple kinds, byteStreamTrackID '" + byteStreamTrackID + "'");
 
                 // If all of |kinds| are expected to succeed, also test each kind individually.
@@ -91,7 +91,13 @@
 
             test(function()
             {
-                checkConstructionFails("audio", "en-US", "label", "this is not a valid sequence", "1");
+                checkConstructionFails("audio", "invalid language", "audio label", VALID_AUDIO_TRACK_KINDS, "1", 'InvalidAccessError');
+
+            }, "Test invalid 'language' parameter syntax passed to TrackDefault constructor");
+
+            test(function()
+            {
+                checkConstructionFails("audio", "en-US", "label", "this is not a valid sequence", "1", new TypeError());
             }, "Test invalid 'kinds' parameter type passed to TrackDefault constructor");
 
             test(function()