refactor: one shared extension-API module, and drive the dApp flows on Firefox (closes #153)

src/shared/walletDelete.js

@@ -1,6 +1,8 @@
 // Wallet and address deletion state transitions, kept out of the views so the
 // selection and broadcast rules are testable without a DOM.
 
+const { notify } = require("./browserApi");
+
 // Two records of the same address can be stored in different cases, so
 // address equality is never a literal string comparison.
 function sameAddress(a, b) {
@@ -144,9 +146,7 @@ function removeAddressFromState(state, walletIdx, addrIdx) {
 // accountsChanged to connected sites. Same call shape as the address
 // switch in the home view.
 function broadcastActiveChanged() {
-    const runtime =
-        typeof browser !== "undefined" ? browser.runtime : chrome.runtime;
-    runtime.sendMessage({ type: "AUTISTMASK_ACTIVE_CHANGED" });
+    notify({ type: "AUTISTMASK_ACTIVE_CHANGED" });
 }
 
 module.exports = {