fix: open no approval window for a site-connection prompt already answered (closes #287)

When a site-connection prompt was decided before the toolbar popup raised
for it had loaded, that popup was torn down, chrome.action.openPopup()
rejected, and the background opened its fallback window for the answered
approval and only then removed it. In the Chrome end-to-end suite the next
test could take that window for its own prompt and lose it under its wait.
openApprovalWindow() now returns before creating a window when the approval
is no longer pending.

The blocklist test clicked its self-closing Reject with a plain click; it
now clicks it as the other site Reject does, with the click witnessed.

Model: opus-5-5

tests/backgroundApproval.test.js

@@ -2235,6 +2235,27 @@ describe("a site connection decided as the popup closes", () => {
         });
     });
 
+    // The prompt is decided before the toolbar popup raised for it has
+    // loaded; that popup is torn down and openPopup() rejects only after.
+    test("a toolbar prompt already decided opens no window when openPopup() rejects", async () => {
+        const bg = loadBackground({ actionPopup: true });
+        const opening = deferred();
+        bg.openPopup.mockImplementation(() => opening.promise);
+        const pending = bg.requestSite();
+        await settle();
+
+        const port = bg.connectApproval(pending.id());
+        port.decide(true, false);
+        port.disconnect();
+        await settle();
+        expect(pending.result()).toEqual({ result: [signer.address] });
+
+        opening.reject(new Error("the toolbar popup closed before it loaded"));
+        await settle();
+
+        expect(bg.created).toHaveLength(0);
+    });
+
     // The port carries a decision now, so it carries the sender check the
     // one-off message used to carry. A content script that guessed an
     // approval id must not be able to connect the site it is running on.