Fix success or failed determine code bug

currently implementation was erroneous decision, e.g. _infrastructure/tests/typescript/tsc.js not exists.
Fix latent bug it found by prev commit, avoid unexpected callback happen.

maxBuffer’s default is 200*1024 byte in Node.js require('child_process').exec
but…
$ node _infrastructure/tests/typescript/tsc.js --noImplicitAny threejs/three-tests.ts 2>&1 > /dev/null | wc
    1963   21628  291809
over 200KB, when exec method called callback function, but it is not completed yet. exitCode === undefined.
Suppress test failed
Merge pull request #1309 from vvakame/fix-maxBuffer-bug

Fixed a bug, there is a test should fail if the original