Auto merge of #11542 - asajeffrey:mozbrowser-send-opentab-event, r=paulrouget

Fire a mozbrowseropenwindow event when an html anchor has a non-self target

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When an html anchor has a non-self target, fire a `mozbrowseropenwindow` event.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #11539.
- [X] These changes do not require tests because we don't have the infrastructure for mozbrowser testing yet.

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components/script/dom/webidls/BrowserElement.webidl

@@ -83,6 +83,19 @@ dictionary BrowserShowModalPromptEventDetail {
   // TODO(simartin) unblock() callback
 };
 
+dictionary BrowserElementOpenTabEventDetail {
+  // https://developer.mozilla.org/en-US/docs/Web/Events/mozbrowseropentab
+  DOMString url;
+};
+
+dictionary BrowserElementOpenWindowEventDetail {
+  // https://developer.mozilla.org/en-US/docs/Web/Events/mozbrowseropenwindow
+  DOMString url;
+  DOMString target;
+  DOMString features;
+  // Element frameElement;
+};
+
 BrowserElement implements BrowserElementCommon;
 BrowserElement implements BrowserElementPrivileged;