Bug 1702271 - Document waitForCondition msg arg. r=florian DONTBUILD

This also makes a couple of other fixes to existing comments to bring them in
line with the actual behaviour and names used.

Differential Revision: https://phabricator.services.mozilla.com/D110428

testing/modules/TestUtils.jsm

@@ -149,12 +149,17 @@ var TestUtils = {
    *
    * @param condition
    *        A condition function that must return true or false. If the
-   *        condition ever throws, this is also treated as a false. The
-   *        function can be an async function.
+   *        condition ever throws, this function fails and rejects the
+   *        returned promise. The function can be an async function.
+   * @param msg
+   *        A message used to describe the condition being waited for.
+   *        This message will be used to reject the promise should the
+   *        wait fail. It is also used to add a profiler marker in the
+   *        success case.
    * @param interval
    *        The time interval to poll the condition function. Defaults
    *        to 100ms.
-   * @param attempts
+   * @param maxTries
    *        The number of times to poll before giving up and rejecting
    *        if the condition has not yet returned true. Defaults to 50
    *        (~5 seconds for 100ms intervals)