Make behaviour of ChatInviteDialog more consistent

* Pressing enter now always adds whatever was in the input box
   to the invite list, if it's a valid address (previously it
   added it to the list of it was a search result but submitted
   the form straight away if there were no results).
 * Remove isValidAddress as it was only used in the context of
   testing whether its return value was true or null (where null
   meant "unsure") so just use getAddressType instead.

src/Invite.js

@@ -59,25 +59,3 @@ export function inviteMultipleToRoom(roomId, addrs) {
     return this.inviter.invite(addrs);
 }
 
-/**
- * Checks is the supplied address is valid
- *
- * @param {addr} The mx userId or email address to check
- * @returns true, false, or null for unsure
- */
-export function isValidAddress(addr) {
-    // Check if the addr is a valid type
-    var addrType = this.getAddressType(addr);
-    if (addrType === "mx") {
-        let user = MatrixClientPeg.get().getUser(addr);
-        if (user) {
-            return true;
-        } else {
-            return null;
-        }
-    } else if (addrType === "email") {
-        return true;
-    } else {
-        return false;
-    }
-}

src/components/views/dialogs/ChatInviteDialog.js

@@ -74,8 +74,8 @@ module.exports = React.createClass({
         var inviteList = this.state.inviteList.slice();
         // Check the text input field to see if user has an unconverted address
         // If there is and it's valid add it to the local inviteList
-        var check = Invite.isValidAddress(this.refs.textinput.value);
-        if (check === true || check === null) {
+        const addrType = Invite.getAddressType(this.refs.textinput.value);
+        if (addrType !== null) {
             inviteList.push(this.refs.textinput.value);
         } else if (this.refs.textinput.value.length > 0) {
             this.setState({ error: true });
@@ -135,12 +135,26 @@ module.exports = React.createClass({
         } else if (e.keyCode === 13) { // enter
             e.stopPropagation();
             e.preventDefault();
-            this.onButtonClick();
+            if (this.state.queryList.length > 0) {
+                this.addressSelector.chooseSelection();
+            } else {
+                const addrType = Invite.getAddressType(this.refs.textinput.value);
+                if (addrType !== null) {
+                    const inviteList = this.state.inviteList.slice();
+                    inviteList.push(this.refs.textinput.value.trim());
+                    this.setState({
+                        inviteList: inviteList,
+                        queryList: [],
+                    });
+                } else {
+                    this.setState({ error: true });
+                }
+            }
         } else if (e.keyCode === 188 || e.keyCode === 9) { // comma or tab
             e.stopPropagation();
             e.preventDefault();
-            var check = Invite.isValidAddress(this.refs.textinput.value);
-            if (check === true || check === null) {
+            const addrType = Invite.getAddressType(this.refs.textinput.value);
+            if (addrType !== null) {
                 var inviteList = this.state.inviteList.slice();
                 inviteList.push(this.refs.textinput.value.trim());
                 this.setState({