Add use counter for attachInternals()

This previously had no use counter.

I'm adding NOTRY here because branch day seems to be an
impossible day to land changes to enums.xml. Hopefully this
sails through. Feel free to revert if this breaks something.
NOTRY=true

Bug: 905922
Change-Id: I613782dc839a9afc9bce93406200557e4f81c024
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2363361
Commit-Queue: Mason Freed <masonfreed@chromium.org>
Auto-Submit: Mason Freed <masonfreed@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800189}

third_party/blink/public/mojom/web_feature/web_feature.mojom

@@ -2761,6 +2761,7 @@ enum WebFeature {
   kBluetoothAdvertisingEventTxPower = 3432,
   kCrossOriginOpenerPolicyReporting= 3433,
   kGamepadId = 3434,
+  kElementAttachInternals = 3435,
 
   // Add new features immediately above this line. Don't change assigned
   // numbers of any item, and don't reuse removed slots.

third_party/blink/renderer/core/html/html_element.cc

@@ -1596,6 +1596,7 @@ ElementInternals* HTMLElement::attachInternals(
         "ElementInternals for the specified element was already attached.");
     return nullptr;
   }
+  UseCounter::Count(GetDocument(), WebFeature::kElementAttachInternals);
   SetDidAttachInternals();
   return &EnsureElementInternals();
 }

tools/metrics/histograms/enums.xml

@@ -28866,6 +28866,7 @@ Called by update_use_counter_feature_enum.py.-->
   <int value="3432" label="BluetoothAdvertisingEventTxPower"/>
   <int value="3433" label="CrossOriginOpenerPolicyReporting"/>
   <int value="3434" label="GamepadId"/>
+  <int value="3435" label="ElementAttachInternals"/>
 </enum>
 
 <enum name="FeaturePolicyAllowlistType">