Fix LayoutTableSectionTest test cases which called a method on nil.

testing/buildbot/chromium.fyi.json

Index: testing/buildbot/chromium.fyi.json
diff --git a/testing/buildbot/chromium.fyi.json b/testing/buildbot/chromium.fyi.json
index 3f258402994679baf8f7afdb45a2bbf32676a53d..22050a82f68c421f1122857adbf64857635931cd 100644
--- a/testing/buildbot/chromium.fyi.json
+++ b/testing/buildbot/chromium.fyi.json
@@ -4473,6 +4473,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "net_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "pdf_unittests"
       },
       {
@@ -4522,6 +4528,12 @@
           "can_use_on_swarming_builders": true
         },
         "test": "url_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "webkit_unit_tests"
       }
     ]
   },
@@ -12376,6 +12388,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "webkit_unit_tests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "wm_unittests"
       },
       {