Remove @author tags (#5601)

Our files are up to a decade old, and have churned so much, that the initial author of the file no longer has much meaning.

Furthermore, this will encourage developers to post to the developer group, rather than emailing Googlers (usually me) directly.

core/utils/string.js

@@ -8,7 +8,6 @@
  * @fileoverview Utility methods for string manipulation.
  * These methods are not specific to Blockly, and could be factored out into
  * a JavaScript framework such as Closure.
- * @author fraser@google.com (Neil Fraser)
  */
 'use strict';