Revert of Add fuzzer for AXTree and fix a couple of bugs it found.

ui/accessibility/BUILD.gn

Index: ui/accessibility/BUILD.gn
diff --git a/ui/accessibility/BUILD.gn b/ui/accessibility/BUILD.gn
index f1c43b744758e9a45e9be729276f8a0a0962daae..4c03ce91d34e55a5f9e7465509fafdb339a30adc 100644
--- a/ui/accessibility/BUILD.gn
+++ b/ui/accessibility/BUILD.gn
@@ -6,7 +6,6 @@
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/json_schema_api.gni")
-import("//testing/libfuzzer/fuzzer_test.gni")
 import("//testing/test.gni")
 if (is_android) {
   import("//build/config/android/rules.gni")
@@ -154,13 +153,3 @@
   root_namespace = "ui"
   schemas = true
 }
-
-fuzzer_test("ax_tree_fuzzer") {
-  sources = [
-    "ax_tree_fuzzer.cc",
-  ]
-
-  deps = [
-    ":accessibility",
-  ]
-}