Normalize paths when looking up items on outputCache

[cspotcode]

Fixes #1037

• add regression test. Intentionally throw an error, assert that the line number is correct

[coveralls]

Coverage remained the same at 81.137% when pulling f588826 on ab/fix-source-maps-on-windows into 2397f3a on master.

[cspotcode]

The failures look like a mistake in how I set up the CI stuff. I need to mark those Coveralls - run-* executions as not affecting the CI success/failure.

[cspotcode]

Results of manual, local test, using the reproduction from #1037. Line number is correct.

Since our build script spits out a tarball now, this made it easy to switch from Linux to Windows, install the tarball, and test.

D:\Personal-dev\@TypeStrong\ts-node-repros\1037>npm install ..\..\ts-node\tests\ts-node-packed.tgz
npm WARN 1037 No repository field.
npm WARN 1037 No license field.

+ ts-node@8.10.1
updated 1 package and audited 9 packages in 1.053s
found 0 vulnerabilities


D:\Personal-dev\@TypeStrong\ts-node-repros\1037>.\node_modules\.bin\ts-node.cmd .\example.ts

D:\Personal-dev\@TypeStrong\ts-node-repros\1037\example.ts:8
    throw new Error("aaa")
          ^
Error: aaa
    at main (D:\Personal-dev\@TypeStrong\ts-node-repros\1037\example.ts:8:11)
    at Object.<anonymous> (D:\Personal-dev\@TypeStrong\ts-node-repros\1037\example.ts:17:3)
    at Module._compile (internal/modules/cjs/loader.js:1185:30)
    at Module.m._compile (D:\Personal-dev\@TypeStrong\ts-node-repros\1037\node_modules\ts-node\src\index.ts:858:23)
    at Module._extensions..js (internal/modules/cjs/loader.js:1205:10)
    at Object.require.extensions.<computed> [as .ts] (D:\Personal-dev\@TypeStrong\ts-node-repros\1037\node_modules\ts-node\src\index.ts:861:12)
    at Module.load (internal/modules/cjs/loader.js:1034:32)
    at Function.Module._load (internal/modules/cjs/loader.js:923:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
    at main (D:\Personal-dev\@TypeStrong\ts-node-repros\1037\node_modules\ts-node\src\bin.ts:227:14)

D:\Personal-dev\@TypeStrong\ts-node-repros\1037>

[cspotcode]

I wasn't 100% sure that the sourcemap tests were proving that line numbers are correct. So I added a silly amount of whitespace to be sure.