Get rid of unnecessary speech logs from ChromeVox

The start and end callback logs were from a long time ago when those were
new and not as stable. Get rid of them now.

BUG=none

Review URL: https://codereview.chromium.org/1062203002

Cr-Commit-Position: refs/heads/master@{#324284}

chrome/browser/resources/chromeos/chromevox/chromevox/injected/console_tts.js

@@ -42,14 +42,6 @@ cvox.ConsoleTts.prototype.speak = function(textString, queueMode, properties) {
     }
     logStr += ' "' + textString + '"';
     window['console']['log'](logStr);
-
-    if (properties && properties['startCallback'] != undefined) {
-      window.console.log('  using startCallback');
-    }
-
-    if (properties && properties['endCallback'] != undefined) {
-      window.console.log('  using endCallback');
-    }
   }
   return this;
 };