lib: disable eslint rule in trace_mgr.js

The error created isn't ever thrown, it's just used to get an
approximate stack.

PR-URL: #502
Reviewed-By: Seth Brenith <sethb@microsoft.com>

Author: kfarnung

lib/trace_mgr.js

@@ -476,7 +476,8 @@ const directIsAbsolute = (process.platform === 'win32') ?
 * Create and return a fuzzy stack match for the current call.
 */
 function generateFuzzyStack(eventKind) {
-  //Create an array of the file/lines for user space code in the call stack
+  // Create an array of the file/lines for user space code in the call stack.
+  // eslint-disable-next-line no-restricted-syntax
   let errstk = new Error()
     .stack
     .split('\n')