Detect fs case sensitivity based on it's real behavior

[koroandr]

TypeScript Version: 1.8.10

Code

In src/compiler/sys.ts there is such line (316):

const useCaseSensitiveFileNames = platform !== "win32" && platform !== "win64" && platform !== "darwin";

It detects case-sensitivity based on platform name, which is considered a bad practice.

I am working on Mac OS system with case-sensitive file system, so it's broken for me (I faced the problem with it while using tsify.

Expected behavior:
File system case sensitivity detection is based on it's real behavior.
Actual behavior:
File system case sensitivity detection is based on platform name.