Fix flaky compilation on mac-arm64-rel

third_party/blink/renderer/bindings/core/v8/v8/v8_computed_accessible_node.cc
(a generated file) indirectly includes
ui/accessibility/ax_enums.mojom-blink-forward.h but without
a dependency we cannot guarantee that this is generated before.

The exact include chain is:
third_party/blink/renderer/bindings/core/v8/v8_computed_accessible_node.cc:8:
third_party/blink/renderer/bindings/core/v8/v8_computed_accessible_node.h:11:
third_party/blink/renderer/core/aom/computed_accessible_node.h:12:
third_party/blink/renderer/core/accessibility/ax_object_cache.h:33:
third_party/blink/renderer/core/accessibility/blink_ax_event_intent.h:19:10:
ui/accessibility/ax_enums.mojom-blink-forward.h

Adds a missing dependency from //third_party/blink/renderer/core
to //ui/accessibility/mojom.

Bug: 1125509
Change-Id: Ia7132aee1fab7ab9f855b1ba6d233c654caca736
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2396055
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#804756}

third_party/blink/renderer/core/BUILD.gn

@@ -87,6 +87,7 @@ source_set("prerequisites") {
     "//third_party/ots",
     "//third_party/snappy",
     "//third_party/zlib",
+    "//ui/accessibility/mojom:mojom_blink",
     "//ui/base:features",
     "//ui/base/ime/mojom",
     "//ui/display/mojom:mojom_blink",