Replace send token dropdown with static display when token is locked

When sending from the address-token view, show the token symbol as
plain text instead of a disabled dropdown. ERC-20 tokens include an
etherscan link to the contract address. The dropdown is restored when
navigating back or entering send from other views.

src/popup/views/home.js

@@ -403,7 +403,8 @@ function init(ctx) {
         }
         $("send-to").value = "";
         $("send-amount").value = "";
-        $("send-token").disabled = false;
+        $("send-token").classList.remove("hidden");
+        $("send-token-static").classList.add("hidden");
         renderSendTokenSelect(addr);
         updateSendBalance();
         showView("send");