Add clear() to Element.classList.

sky/tests/lowlevel/classlist-expected.txt

Index: sky/tests/lowlevel/classlist-expected.txt
diff --git a/sky/tests/lowlevel/classlist-expected.txt b/sky/tests/lowlevel/classlist-expected.txt
index 523cc429d6978b5192bfb879cd88a5dc7ccbed10..a924cfc8d8326b8f88e6f57c4c91560699b3f438 100644
--- a/sky/tests/lowlevel/classlist-expected.txt
+++ b/sky/tests/lowlevel/classlist-expected.txt
@@ -1,12 +1,13 @@
-Running 8 tests
+Running 9 tests
 ok 1 Class list should add multiple classes
 ok 2 Class list should add classes in order
 ok 3 Class list should remove classes
 ok 4 Class list should remove multiple classes
-ok 5 Class list should check for classes
-ok 6 Class list should get classes by index
-ok 7 Class list should toggle classes
-ok 8 Class list should dynamically update style
-8 tests
-8 pass
+ok 5 Class list should clear all classes
+ok 6 Class list should check for classes
+ok 7 Class list should get classes by index
+ok 8 Class list should toggle classes
+ok 9 Class list should dynamically update style
+9 tests
+9 pass
 0 fail