Add assert descriptions to fontfaceset-check-platform-fonts.html

third_party/WebKit/LayoutTests/fast/css/fontfaceset-check-platform-fonts.html

Index: third_party/WebKit/LayoutTests/fast/css/fontfaceset-check-platform-fonts.html
diff --git a/third_party/WebKit/LayoutTests/fast/css/fontfaceset-check-platform-fonts.html b/third_party/WebKit/LayoutTests/fast/css/fontfaceset-check-platform-fonts.html
index 5263db68bc96285957927eece2c16649cbaeeabc..81473a4c876e1db54d3b6d13ddd7cdf5f4ca5386 100644
--- a/third_party/WebKit/LayoutTests/fast/css/fontfaceset-check-platform-fonts.html
+++ b/third_party/WebKit/LayoutTests/fast/css/fontfaceset-check-platform-fonts.html
@@ -4,11 +4,11 @@
 <script>
 
 test(() => {
-  assert_true(document.fonts.check('10px Arial'));
-  assert_false(document.fonts.check('10px Nonexistent'));
-  assert_true(document.fonts.check('10px sans-serif'));
-  assert_true(document.fonts.check('10px Nonexistent, monospace'));
-  assert_false(document.fonts.check('10px Nonexistent1, Nonexistent2'));
+  assert_true(document.fonts.check('10px Arial'), 'Arial');
+  assert_false(document.fonts.check('10px Nonexistent'), 'Nonexistent');
+  assert_true(document.fonts.check('10px sans-serif'), 'sans-serif');
+  assert_true(document.fonts.check('10px Nonexistent, monospace'), 'Nonexistent, monospace');
+  assert_false(document.fonts.check('10px Nonexistent1, Nonexistent2'), 'Nonexistent1, Nonexistent2');
 }, 'Tests FontFaceSet#check() returns true for platform fonts');
 
 </script>