Tests fail for Node.js >= 12

[nileshpatra]

Hi, the tests fail for Node.js >= 12. Here's the log:

*[master][~/ups/string_decoder]$ npm run test
(node:5240) [DEP0005] DeprecationWarning: Buffer() is deprecated due to security and usability issues. Please use the Buffer.alloc(), Buffer.allocUnsafe(), or Buffer.from() methods instead.

> string_decoder@1.3.0 test /home/nilesh/ups/string_decoder
> tap test/parallel/*.js && node test/verify-dependencies

assert.js:132
  throw err;
  ^

AssertionError [ERR_ASSERTION]: Unexpected global(s) found: queueMicrotask
    at process.<anonymous> (/home/nilesh/ups/string_decoder/test/common/index.js:500:12)
    at process.emit (events.js:210:5) {
  generatedMessage: false,
  code: 'ERR_ASSERTION',
  actual: undefined,
  expected: undefined,
  operator: 'fail'
}
not ok test/parallel/test-string-decoder-end.js ......... 0/1
    Command: "/usr/bin/node test-string-decoder-end.js"
    TAP version 13
    not ok 1 test/parallel/test-string-decoder-end.js
      ---
        exit:    1
        stderr:  |
          assert.js:132
            throw err;
            ^
          
          AssertionError [ERR_ASSERTION]: Unexpected global(s) found: queueMicrotask
              at process.<anonymous> (/home/nilesh/ups/string_decoder/test/common/index.js:500:12)
              at process.emit (events.js:210:5) {
            generatedMessage: false,
            code: 'ERR_ASSERTION',
            actual: undefined,
            expected: undefined,
            operator: 'fail'
          }
        command: "/usr/bin/node test-string-decoder-end.js"
      ...
    
    1..1
    # tests 1
    # fail  1
    
assert.js:132
  throw err;
  ^

AssertionError [ERR_ASSERTION]: Unexpected global(s) found: queueMicrotask
    at process.<anonymous> (/home/nilesh/ups/string_decoder/test/common/index.js:500:12)
    at process.emit (events.js:210:5) {
  generatedMessage: false,
  code: 'ERR_ASSERTION',
  actual: undefined,
  expected: undefined,
  operator: 'fail'
}
not ok test/parallel/test-string-decoder.js ............. 0/1
    Command: "/usr/bin/node test-string-decoder.js"
    TAP version 13
    not ok 1 test/parallel/test-string-decoder.js
      ---
        exit:    1
        stderr:  |
          assert.js:132
            throw err;
            ^
          
          AssertionError [ERR_ASSERTION]: Unexpected global(s) found: queueMicrotask
              at process.<anonymous> (/home/nilesh/ups/string_decoder/test/common/index.js:500:12)
              at process.emit (events.js:210:5) {
            generatedMessage: false,
            code: 'ERR_ASSERTION',
            actual: undefined,
            expected: undefined,
            operator: 'fail'
          }
        command: "/usr/bin/node test-string-decoder.js"
      ...
    
    1..1
    # tests 1
    # fail  1
    
total ................................................... 0/2

not ok
npm ERR! code ELIFECYCLE
npm ERR! errno 2
npm ERR! string_decoder@1.3.0 test: `tap test/parallel/*.js && node test/verify-dependencies`
npm ERR! Exit status 2
npm ERR! 
npm ERR! Failed at the string_decoder@1.3.0 test script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/nilesh/.npm/_logs/2020-01-22T17_03_37_159Z-debug.log