No need for custom getter for callback selectors.

The generated method also returns a const Vector<String>&.

Change-Id: Ib2754f596881009d249d70509ee7d196f86180ad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2134254Reviewed-by: Manuel Rego <rego@igalia.com>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756227}

third_party/blink/renderer/core/style/computed_style.cc

@@ -1072,7 +1072,7 @@ void ComputedStyle::UpdateIsStackingContext(bool is_document_element,
 }
 
 void ComputedStyle::AddCallbackSelector(const String& selector) {
-  if (!CallbackSelectorsInternal().Contains(selector))
+  if (!CallbackSelectors().Contains(selector))
     MutableCallbackSelectorsInternal().push_back(selector);
 }
 

third_party/blink/renderer/core/style/computed_style.h

@@ -1256,9 +1256,6 @@ class ComputedStyle : public ComputedStyleBase,
   CSSTransitionData& AccessTransitions();
 
   // Callback selectors.
-  const Vector<String>& CallbackSelectors() const {
-    return CallbackSelectorsInternal();
-  }
   void AddCallbackSelector(const String& selector);
 
   // Non-property flags.

third_party/blink/renderer/core/style/computed_style_extra_fields.json5

@@ -638,7 +638,7 @@
       default_value: "Vector<String>()",
       include_paths: ["third_party/blink/renderer/platform/wtf/vector.h",
                       "third_party/blink/renderer/platform/wtf/text/wtf_string.h"],
-      computed_style_custom_functions: ["getter", "setter"],
+      computed_style_custom_functions: ["setter"],
     },
     {
       name: "PaintImages",