Added stream_data.get_name().

This function returns the stream's actual name, if we can get it;
otherwise, it's the identity function.

(imported from commit 7a981adba9632d6c6eba54cb6514a9226d1e83e8)

static/js/stream_data.js

@@ -75,6 +75,19 @@ exports.get_invite_only = function (stream_name) {
     return sub.invite_only;
 };
 
+exports.get_name = function (stream_name) {
+    // This returns the actual name of a stream if we are subscribed to
+    // it (i.e "Denmark" vs. "denmark"), while falling thru to
+    // stream_name if we don't have a subscription.  (Stream names
+    // are case-insensitive, but we try to display the actual name
+    // when we know it.)
+    var sub = exports.get_sub(stream_name);
+    if (sub === undefined) {
+        return stream_name;
+    }
+    return sub.name;
+};
+
 return exports;
 
 }());

zerver/tests/frontend/node/stream_data.js

@@ -36,4 +36,7 @@ var stream_data = require('js/stream_data.js');
 
     assert(stream_data.get_invite_only('social'));
     assert.equal(stream_data.get_color('social'), 'red');
+
+    assert.equal(stream_data.get_name('denMARK'), 'Denmark');
+    assert.equal(stream_data.get_name('unknown Stream'), 'unknown Stream');
 }());