Bug 1573978 [wpt PR 18436] - Update wpt metadata, a=testonly

wpt-pr: 18436
wpt-type: metadata

testing/web-platform/meta/element-timing/toJSON.html.ini

@@ -0,0 +1,4 @@
+[toJSON.html]
+  [Test toJSON() in PerformanceElementTiming.]
+    expected: FAIL
+

testing/web-platform/meta/event-timing/toJSON.html.ini

@@ -0,0 +1,4 @@
+[toJSON.html]
+  [Test toJSON() in PerformanceEventTiming.]
+    expected: FAIL
+

testing/web-platform/meta/largest-contentful-paint/toJSON.html.ini

@@ -0,0 +1,4 @@
+[toJSON.html]
+  [Test toJSON() in LargestContentfulPaint.]
+    expected: FAIL
+

testing/web-platform/meta/layout-instability/toJSON.html.ini

@@ -0,0 +1,4 @@
+[toJSON.html]
+  [Test toJSON() in LayoutShift.]
+    expected: FAIL
+